While there are answers to some aspects of this issue, other times
the solutions run contrary to what one may believe would work..
Here's a compilation of links to try & use to resolve the matter
where too little storage is available for the user files & macOS.
• Q: "how can i add more storage?" - Apple Community [reply & links]
https://discussions.apple.com/thread/253606231?answerId=256750449022#256750449022
To supplement by use of external storage, is one good way to try.
Additional ones are share some details across their linked content.