I have been seeing people not realize that you can play bot-only lobbies for practice (very basic anyway), to screw around by yourself or your friends, or to just have a more chill experience after your casual matches run out. You will also need to be a clan master which costs 15k BP to create these lobbies, which is pretty cheap and not hard to earn.
Unfortunately you can only configure bot damage and amount of bots to join but allegedly Krafton is adding more customizable behavior for bots in the future plus bot improvements. And no progression is allowed obviously since this is a custom game.
You should be able to play most if not all maps but limited to the 3 presets in the screenshot in the normal BR mode.