This is not possible due to the massive architectural differences between GBA and GB(C).
However, there are some fairly approachable GBA development toolkits like Natu, Butano, etc. and plenty of guidance from the Tonc book, if you want to make GBA games.
You can play the games you make on an iPad.
You cannot make games using GB Studio on an iPad.
GB Studio only runs on Linux, Mac, and Windows computers.