If, and only if the developers include controller support. Which they largely don't, even when controllers are supported on every other platform.
Two egregious examples: The Final Fantasy Pixel Remastered series, and Monster Hunter Stories. The first has controller support on both the PC and consoles, but not on phones (which came out first). The second launched on a console (the 3DS), and has no controller support on the phone.
That caveat alone makes it so frustrating to play games on the phone IME.
It’s a shame because the UX of controller configuration on iOS/macOS/tvOS is the best I’ve seen outside of consoles. Even Windows, the king of gaming, doesn’t do as well with configuration of Microsoft’s own Xbox controllers (let alone those of competing companies). Instead on Windows Steam is required for any level of sanity with controllers.
Even if they do include, it's often weird. I wanted to try play genshin with controller - you have to complete certain parts of the game to unlock settings button. Why?
Once the A17 makes its way to the iPad mini, that'll be even closer.