AI work beyond simple value tweaking is generally quite an undertaking. 99.99% of the AI's code is located in CvGameCoreDLL, and the remaining 0.01% is located in the game's SQL data as behavior lists or a couple of editable values (have a look at my Civ6 AI cleanup mod if you want a starting off point for the latter). If you want to start working on the AI immediately, you should start browsing the game's SQL databases and having a look at the behavior lists, but there's probably less you can influence regarding the AI with XML/SQL modding than you could with Civ5, and even Civ5 was quite limited. You'll most likely want to learn C++ then, since if/when CvGameCoreDLL's source code is released, it will undoubtedly be a 100000+ line jungle of C++ code, so you'll definitely want to not just know, but be comfortable with C++ to be able to hack away at the jungle.
Since AI modding requires DLL modding, most people who end up working on the AI don't actually dedicate themselves to AI work. Instead, they usually start out with some total conversion or large overhaul mod, then slowly start fiddling with the AI even as they focus on other stuff. Based on my experiences with AI modding in Civ5, AI modding is basically an "if you build it, they will come" affair. Many people say they're interested in AI modding, so posting about asking who wants to help out will barely draw any serious attention (or at least that's what happened with me), but as soon as you start actually posting some of your own work, it'll draw in people who might not have otherwise wanted to work on the AI to help you out in some way.