I often find that I need to go to three places to reset changes:
The template management screen
The template part management screen
The styles sidebar
On the template and part management screens, I miss an option to reset all my items with one click.
In general I miss an option to reset all my user made changes, so both custom CSS, block style changes, template part markup changes, and template markup changes.
The option for me is to install and use a third party reset plugin, but those delete all my content and deactivate my current theme and plugins.
This idea is from @carolinan from this GB issue: https://github.com/WordPress/gutenberg/issues/54958.
Related to https://github.com/WordPress/create-block-theme/issues/494.