I assume your ok for internal storage @Chrisjh
If you are then first try opening settings, apps, camera, storage, clear data and cache etc and then try launching the camera again.
If no joy and a soft reboot by turning the phone off and on does not help then you may want to consider a factory reset after backing up and remove any relevant Sd card.
Daily Driver > Samsung Galaxy s²⁵ Ultra 512Gb ~ Titanium Black.
The advice I offer is my own and does not represent Samsung’s position.
I'm here to help. " This is the way. "
