It's possible for users to hide/show document libraries within the Workspace 365 Document app. This function is optional (introduced with opt-out) as it brings a level of self service to users which some organizations might not prefer. You can enable it as an Workspace 365 admin. Go to settings and "SharePoint documents". Here you can enable 'Allow users to hide/show libraries'.
Admin: Go to settings, SharePoint documents and enable 'Allow users to hide/show libraries'
Result for users: When enabling this feature users are now able to hide/show libraries, this decreases the amount of clutter which they face when searching documents or folders. Imagine someone who has the rights to access 100 projects, now they can hide the 90 projects on which they are currently not working.
Users can navigate to the Document view settings by going to their settings via their profile picture or from the Document app by clicking on the eye icon.