Is there a possbility to add a custom field like the subject field in tasks with recommendations?

Hello everybody,

I would like to give our sales the chance to add a text to a quote template, where they can pick a predefined title and optional also change this predefined sentence.

This possiblity is available in tasks, where I can predefine some text for the subject field, but I also can add only a text.

Does anybody know if this would be possible for a custom field, or is this funciontality only available at the subject field of tasks.

Thank you, best