I have query on sim card
I need to insert a SIM card into an iPhone XR
iPhone 6s, iOS 15
See if this article helps:
Remove or switch the SIM card in your iPhone - Apple Support
FYI, your Xr can use an eSIM.
Your carrier might be able to provision your SIM over-the-air with no physical SIM being required.
More info on this matter is available here:
About eSIM on iPhone - Apple Support