This app was mentioned in 2 comments, with an average of 2.00 upvotes
I normally can't stand idle games, but I found that I quite enjoyed Idle Crusade. It sounds pretty similar to what you described.
Your party will constantly fight monsters, slowly gaining experience and picking up items. You choose when to fight the boss when you think that they're ready, or pull them into PVP fights and event boss fights to get rare loot.
It's quite IAP heavy, with some stuff locked away behind paywalls where you need to buy enough IAPs to increase a kind of loyalty level before they'll let you upgrade some features. Although they're probably not needed, those features felt useful enough for me to give up on the game. There wasn't an option to just straight-out buy those features, and I wasn't prepared to spend enough to meet a specific level only to find out that the next tier cost ten times the amount. Sorry, but I can't remember what those features were exactly as this was quite a while ago.
Your mileage may vary though. There's a subreddit at /r/IdleCrusade if you're interested.