At any time, you can modify the template you have already created by adding fields, text blocks,... via the "Template Builder" feature under your profile picture.
!!Watch out!! Be aware that all existing content created from this template will be affected by this change.
If you decide to delete a structured field, the information in this field for all the existing contents will be found at the end of the content.
It is not possible to change the type of structured field of a model once it has been saved.