the iphoen was given to me. but is lock how can i unlock it. is A1549
Well. this phone was given to me. the previous owner was going to throw it away. so i ask for it. he did mention it it was locked. but that I could unlocked.
Question marked as
If you mean activation locked, only the previous owner can do that.
If you mean PIN code locked, you will need to restore the phone:
If you forgot your iPhone passcode - Apple Support
If you mean carrier locked, only the cellular carrier the device was locked to can do that.
An A1549 is an iPhone 6, which is not capable of running any version of iOS newer than iOS 12.5.7.