change format in existing project?

Is it possible to change format in an existing project from “manuscript” to non-fiction?

Absolutely. The starting template that you use is basically just a copy – there is no link between a template and a project once the project is created. Think of it like a pizza – if you start your order with a “Hawaiian” pizza you’ll have a potential pizza that includes a crust, marinara sauce, cheese, Canadian bacon, and pineapple, but from that point on there’s nothing that prevents you from adding bacon, removing the pineapple, changing the sauce from marinara to alfredo, or making any other addition/subtraction that you want.

There is no way to say “make it like this template instead” but you can make any changes you need/want to manually.

You can also create a new project using the desired template, open the old project and the new project side-by-side, and then drag and drop items between them if you have content you want to carry over. If you have custom metadata, make sure that the new project has the same custom metadata fields set up first, and then the metadata will also carry over.

What specific thing are you trying to change?