We identified Project Templates as a huge contributor to our adoption strategy, saving our users' time and increasing quality (win-win). Copy Project is lacking. It requires knowledge from the user of prior projects, and there is no concept of "approved" or "good." The point of entry is limiting as well.

Our preferred behavior:
Select Templates: User has an option to create +New (Project from scratch) or +New (Project from Template Library)
Template Library has a list of project templates: Name, Description, Owner, Last Updated, Number of times used, etc. Templates come in as a new project with all tasks, task dependencies, generic resources, effort, duration; the user simply enters a project start date, and all dates cascade from this entry.

Create Templates: There is a means for approving templates. User clicks to "Create Template." The project template is either displayed in the Template Library with an indication it is Draft, or it is required to be approved by a user in an elevated role. We have a similar concept in our Resource Hub via PowerAutomate workflow: Users select skills, and Leads Verify those skills.

Manage Templates: certain Users can update/edit existing templates.

All of this behavior could be similar to how Views work as well, where anyone can create a view and share it with others.