Templates as content I currently have a project with the requirement to edit templates for content like content, i.e. we will have a template content type which will be used as template for another content type.

I've looked for projects and best practices on the matter but didn't find anything. Does someone have experiences with a similar setup?

Should I use Twig and inline_template or should I write my own template system with tokens? Other ideas? 

Any help is greatly appreciated!
It sounds like what the client really wants is something like the Paragraphs module:

https://www.drupal.org/project/paragraphs

It's a good solution for creating flexible, yet structured, content.

Take a look at this video for a good idea of the promises (and pitfalls) of this approach:

https://www.oomphinc.com/notes/2018/11/component-based-design-system-drupal-8-paragraphs/