PIKACHUK'S PROFILE

I wondered how versatile is rpg maker ?
for instance often when I saw games made with RPG maker, they often had the exact same artstyle, often used the same kind of textboxes, menus, ost style etc

as a C#/C++ programmer and a composer, I was wondering how versatile rpg maker is because I'd like to make unique games, so is it possible for instance to modify absolutely everything such as the battle system (for instance making it as action rpg instead of rpg) the UI, the graphics (using HD spritesheets instead of pixel art snes-esque ones) etc
I saw that rpg maker MV uses javascript, since it's a highly more "high level" language than C++ I don't think it would be that big of a deal to learn, but in this case, is it a kind of "sandboxed" javascript where we can only access some restricted apis or do we have complete freedom over the whole game ?