1. Knowledgable sources: So first i'm not sure how in depth your knowledge on Napoleonic warfare is(Whether you're just getting into or you've been at it for years), but if you are eager and trying to learn thats great :) and then the very first tip I would have is to try not to believe everything you see in popular films and movies set in that time period. The first one that comes to my mind is "Sharpe", great show but a lot inaccuracies which I only learned about much later after delving into the history itself. If you're up for some reading however, I definetly recommend "Napulon.com" as a place to start looking, not only do they list decent sources, but they're SUPER indepth on not just the day to day lives of French troops but also that of the Coalition troops as well(UK/Russia/Austria).

2. What kind of job does your protagonist have: The day to day routine of a Horse Grenadier is gonna be FAR different from that of a skirmisher/rifleman/etc. If you know what exactly your character's(This soldier of yours) rank and troop "type" is, it'll give you a more clear goal on what exactly you should be looking for in terms of historical details on a soldiers daily life. Once again recommending Napulon.com as a great place to start since they also discuss the many nitty gritty details of each different soldier variety found in this time period.

3. Looking for details in unlikely places: Napoleon's Egypt: Invading the middle east, while not a primary source persay and not one that is even set in the main theater of the Napoleonic wars(Europe), does seem to have a reputable bibliography, and even has a ton of references to writings(Even citing primary ones from specialists who actually accompanied Napoleon himself!) and descriptions of the comings and goings of day to day camp life for troops and the various trials and tribulations they might have. From reading it for myself I can say parts of it offer yet another good peek into the lives of the average French soldier.

Basic summary: So a soldier probably wouldn't have that much time to go on "side missions" and fun adventures, his main job was doing his various duties as a soldier which were more often than not....kinda mundane just like most soldiers today! Troops of this time period with only some variation all seemed to have followed a regular schedule consisting of:

a) A morning "reveillez" period to the sound of drums or trumpets or shouts(or all of the above), depending on what army/nation

b) Camp duties(Fetch water, cleaning a barracks if garrisoned, forage if out on campaign etc)

c) Inspections and drills

d) Varying Mess hall meal times if garrisoned somewhere/Field rations if out on campaign

e) More drills

f) Some down time here and there with the occasional oppurtunity to have some "real fun" (Prostitutes, drinking, looting, and other things which I wont discuss etc)

g) If it was assigned to you, sentry duty

h) The most obvious one: Fighting in pitched battles/engaging the enemy when ordered

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Napoleonic combat notes, Infantry only:

1. I've only ever been to civil war and revolutionary war period re-enactments*(yeah no big napoleonic re-enactments over where I am in the US sadly)* , but I can tell you that even though you KNOW that everyones got blanks and the cannons arent real and you're not gonna die, there is something super unnerving about it. For the real soldiers who actually had to fight in these battles being forced to keep ranks in incelement weather conditions and on top of that while getting shot at would take both great leadership by NCOs and steel nerves by the enlisted men. Wounds in this time period were horrific, and while i've yet to find decent depictions of musket/artillery casualties, The paintings done of Troops wounded at Waterloo can give you a good idea on how terrifying the carnage could be

2. These battles were super loud and your character, if he was unlucky enough to be a line infantryman dead center in the action could possibly be temporarily deafened by the sheer volume of en masse musket fire. In the background he'd most likely also hear the low boom of cannons, the dreadful thundering of hooves and cavalry movements, and lots of shouting.

3. It was simply a gut wrenching experience and the average foot soldier most likely had little to no idea about how exactly a battle was going until it was almost entirely evident(Seeing hundreds of your allies running away at once can be a sure sign).

u/the_dinks and I mention a couple of first-hand books from the rank and file during the Napoleonic wars here

The books are 'Diary of a Napoleonic Soldier' by Jakob Brinks, edited (and translated by?) Marc Raeff, and Journal of a Soldier of the Seventy First or Glasgow Regiment From 1806 to 1815, which can be found online.

I forgot about it, but The Life and Adventures of John Nicol, Mariner was in the navy during the war and has a couple of chapters about it. He was illiterate, his story was taken down and published by the same guy who published the 'memoirs of a soldier of the 71st' (both men were from Edinburgh).

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ANYTHING between 1750-1825

Probably setting the net a bit wide there, but if you're interested, I have an old comment here with a link to an account by a French naval lieutenant of an attack on a Māori fort (pā) in 1772 (there's some other stuff there from your period, but nothing by European soldiers). Direct link to the whole thing either (and to the original French, if you want it for anything). I'm not sure I mentioned it in the old post, but the key point of the account, how involved Roux was with everything, might be fictional. The account by the captain of the other ship doesn't mention him, and says the French attack was led by someone else. The details all seem realistic though: regardless of whether Roux was actually in the thick of it solving everything with his brilliant leadership like he says, or just back at the ship twiddling his thumbs.