Like any PC game it is tough to find an IOS equivalent and they are typically not too deep on the RPG side, but I will suggest a few that overall people seem happy with

https://apps.apple.com/us/app/galactic-conflict-rts/id494394854(haven't played, $6, mixed/mostly positive reviews)

https://apps.apple.com/us/app/starlight-tactics-unlimited/id1281698592 (turn-based, maybe skip that one)

https://apps.apple.com/us/app/battlevoid-harbinger/id1010582800 (my top choice)

https://apps.apple.com/us/app/war-of-the-zombie/id605277717 (not in space, but great reviews)

If these don't look great, I've found the "similar games" section at the bottom to be actually helpful in finding similar games you wouldn't see elsewhere in the AppStore, I've gone down a few rabbit holes doing that