Are there games available where grinding actually makes you better the more you grind?

I play Idle Heroes right now and have spent like $70 dollars on it so far but after doing some things there's nothing to do for a long time.

I have downtime throughout my day and would love to get on something and play here and there and make my characters more powerful and stuff and have things to do. I think that's why games like Warframe are so popular since you can effectively grind and get better.

Does something like this exist on IOS?