What endlessfix showed is the way you would normally continue from an auto save file, but, you could also take a peek into the auto save folder, and even if you don’t crash you could copy the latest auto save file out to a backup folder.
To get there, use the Go menu in Finder, choose Go to Folder…, and paste in this path:
~/Library/Application Support/SketchUp 2021/working/SKETCHUP/RecoveredFiles/
Something else that is useful is if your welcome screen has a long list of old recovered files, as shown in endless fix’s screenshot. You can go into that folder and delete all of the previous auto save files that you know you are never going to need. That will tidy up the welcome screen quite a bit.