If I understand your requirement right:
You want different forms depending on "Create Incident From Template" or "Create Incident" is used to create an incident?
If my assumption is right: No, as far as I know this is not possible. For each class in SCSM only one form is possible,
(If the reply was helpful please don't forget to upvote and/or accept as answer, thank you)
Regards
Andreas Baumgarten