If you’ve made edits or customizations to your theme, then it’s recommended to either leave it as it is, or manually go through and transfer your edits to the new version. The reason is, if you update by replacing your old files with the new files, then your old files will be overwritten.
The updates aren’t necessary, they are “addons” and small minor fixes. If you made a lot of changes it’s not worth it to update unless you’re willing to go through your code and transfer the customizations.
If you didn’t make customizations, then you can go ahead and swap out the old theme for the new one. Backup and save your data before doing anything just in case you make an error!