https://muse.jhu.edu, https://www.jstor.org, https://www.tandfonline.com... there are a number more. If you are a college student, most schools have an internal search engine that will check all the databases to which your institution is subscribed, as no single database will have everything. Many larger public libraries will also provide such a service. If you aren't a student somewhere or if your public library doesn't offer that kind of service, https://scholar.google.com is your best bet, as it too will check a lot of different databases, but be aware that it will turn up items that are paywalled and you won't be able to access legally without a subscription.

Have a look in the FAQs, I find it difficult to navigate on the mobile app but I expect there is a similar question in there.

When I was studying my goto place was https://www.jstor.org/. It is an absolute treasure trove of articles, particularly historical ones. It has some of the latest historiographical trains of thought which are pretty fundamental if you want to write an interesting thesis.

The subscription cost is pretty hefty but if you are at an academic institution or know someone who is they may have access.