I am going to cover only a small fragment of the Frankish story since the Franks have existed during the Roman Empire and beyond. Their history is incredibly rich and honestly amazing on how they adapted and conquered. One of the best starting points you can look into are the books Before Germany and France and The Laws of the Salian Franks. If you want to have an idea of what the language that the Franks spoke, Gaul, sounded like the band Eluveitie uses it in their music as they are working with a French university to create a proper reproduction of the language.

Charlemagne's rule style begins before he actually ascends the throne. Pepin the Short was originally Mayor of the Palace and ushered in an over throw of the Merovingian rule. One of the major problems that lead to the Merovingian rule ending was the people in power positions (dukes, counts, Mayor of the Palace) became hereditary which also meant that loyalty was not necessarily to the ruler. There was also the point of legitimacy to rule as the Merovingian rulers claimed their right to rule because their hair was a symbol of their divine right by God to rule. When Pepin succeeded in his overthrow of the current Merovingian rulers he had their heads shaved and sent to a monastery to live out the remainder of their lives. Why all of this backstory? Because when Charlemagne finally came to power after his grandfather's overthrow he did not screw up by having his Duchies and Counties ruled through hereditary means. He ensured that when someone was living off the land he gave them they understood that that land was still his in the end and they were just keeping it in check. If he got a hint that someone was getting too uppity he had no issue removing them from power and placing a new duke or count that was more loyal.

With the loyalty established Charlemagne was able to keep reasonable records of what was going on in his area and would ensure there were proper accommodations for the people. This meant that mills, blacksmiths, wells, and other goods were available and as his empire expanded so did proper trade routes. Now that does not mean every town had a blacksmith since materials were not as abundant, but he did make sure they were more available than before.

For the Frankish identity this is a bit more complex since he was constantly expanding his power and empire which meant a lot of wars. When a people were conquered by Charlemagne they were now part of the empire and were afforded certain benefits, think how the Romans had a change of behavior when they conquered a people. They were now more Frankish than their old identity, but there were parts of that identity that Charlemagne saw as beneficial to his empire so they were not completely wiped out. The biggest thing for the new area was that the person overseeing the region was loyal to Charlemagne. The other part of what it meant to be Frankish in the end was they were the rightful inheritors of the legacy of Rome. So when Charlemagne was finally called the Emperor of the Romans (not yet the Holy Roman Empire, but the seed has been planted) he really pushed to reestablish the legacy.

I'm sure other historians could go on other parts as the Franks, Charlemagne, and the Carolingian line is full of insanity and amazing stories, my personal favorite is Charlemagne's grandson Charles the Bald and Rolo. I hope this extremely brief point is a good taster since a lot of this is far more in depth than what I can write here.

I do like this online encyclopedia point on Charlemagne: https://www.newworldencyclopedia.org/entry/Charlemagne

While wrote a few centuries after Charlemagne the story does some justice to how he is depicted of how he treats his men is Song of Roland.

This is a list of how well Charlemagne expected his Dukes and Counts to keep an inventory: https://sourcebooks.fordham.edu/source/800asnapium.asp

I will note here that after Charlemagne's grandsons took over the empire that he had built just fell apart. The story of how Charles the Bald was viewed by Rolo really hones in on how fragile the empire was and the fact that it was split into three sections when they took over really sealed the empires fate. Decades later the world will see the rise of a Norman called William who will go to England and conqueror the land changing the English language forever. During the crusades all Europeans will be called Franks by the people the encounter. In the span of 400 years the Franks will continue to change and redefine who they are from the death of the Merovingian line through the Crusades the Franks were definitely a power house.