Hi @samsam ,
Do you want to add a button, Label, Text Input box below the whole Edit form?
Based on the scenario that you mentioned, I afraid that there is no direct way to achieve your needs. If you add a button within your Edit screen, it would exist in your Edit screen rather than within the Edit form.
In addition, even though, you could add a button below the Edit form, when you scroll the scrollbar in your Edit form, the added button would be scrolled along with the scrollbar.
As an fixed solution, you could consider add a Custom data card in your Edit form, and then add your button, label, Text Input box within the Custom data card.
More details about adding a Custom data card within Edit form, please check the following GIF screenshot:
Best regards,