Yes, that is normal. The application has a very large size, because it needs a lot of storage for the instruments and sounds. It is still small compared to the same app on the Mac.
On my Mac, I'm seeing this, when I check the storage needed by GarageBand:
This thread has been closed by the system or the community team.
You may vote for any posts you find helpful, or search the Community for additional answers.
GarageBand Taking Too Much Storage Space
Welcome to Apple Support Community
A forum where Apple customers help each other with their products. Get started with your Apple Account.