Can I reset my old phone if it’s linked through iCloud to my new phone and I’m locked out
Can I use my iPhone 13 to reset passcode to open my iPhone XR if they a linked through keychain ?
To reset passcode of iPhone XR you need only a computer see the complete steps in the article If you forgot your iPhone passcode - Apple Support
Note : your old iPhone and iPhone XR are signed in with same Apple ID and password on the same network , the iCloud Keychain is set up between both , but resetting passcode can't be done from old iPhone .