Do not buy the Raspberry Pi Case for Raspberry Pi 5 of you intend to use a HAT.
The website mentions:
HATs can be mounted to the enclosure with stand-offs and GPIO header extenders
Which means you can mount HATs, but they won’t be enclosed in the case.
If you are looking for a simple case which has room for:
I can suggest the Unity V2 HAT for RPi5 from Kiwi Electronics.