We would like to be able to convert a text-based field to a note-based field in custom layouts by editing the field.
Use case: We set up a set of fields to build a report, and one field (path to green) is a text field. We've since realised that this field would better serve us as a note field that can have supporting information and screenshots etc added to it. However, the fields are all mature enough now that we have a bunch of reports pulling from that field, so replacing it will cause a lot of manual work and headaches for the extended team.
We also would expect that the content remains in place.
I have no wish to convert the other way (add limitations by converting from a note to text).
It is currently possible to convert custom fields to a different type. Please see this article for information and reach out to our Customer Success team at email@example.com if you need additional assistance.