The 9th gen iPad with the A13 chip will run any game very well. No issues with games like call of duty at all.
The biggest difference for fast pace games where you will notice a difference is with the pros and their high refresh screens.
Other specs come into play too...
3 GB of RAM vs. up to 8 GB of RAM
A13 vs. the M1 chips
10.2" screen vs. up to 12.9"
64 GB base storage vs. 128 GB or higher base storage
... that said, I got the 9th gen 64 GB model. Even though it's the lowest line, it's still a model that came out in recent months, so it should be "powerful enough". I may do some Apple Arcade games, some "mid-tier" games, and mostly digital board games. More importantly, it was only $320. As much as I'd like to have an iPad in the Air or Pro line, those delve into $600 to $1000 price ranges!