To set the AutoSave feature to always be disabled (when working with OneDrive / SharePoint files), you can take the following steps in each of the M365 applications you wish the change to take effect in.
1
Click "File Tab".
2
Click "Options".
3
Select the "Save" category.
4
Uncheck the "AutoSave files stored in the Cloud by default in Word"
5
Click "OK"
6
Now you just need to restart the application for the change to take effect.
Just repeat the same steps for Excel, PowerPoint, and any other M365 application you no longer want to autosave.
Now when you open up any file in OneDrive or SharePoint, the AutoSave tab should be set to off by default.