Can a SIM card from an iPhone SE 1st gen be used in iPhone SE 3rd gen?
Can 1st gen SE SIM card be used in 3rd gen SE?
[Re-Titled by Moderator]
iPhone SE (Gen 3)
Question marked as
Yes, it has the same nano size.
You need to change it if you want to change your traffic cellular plan to 5G network (if your carrier supports it).
Regards
Giulio