The phone doesn't detect the earphones

hi! this is a rather odd question to ask, but i currently have a second hand iphone 7 plus. i have these earphones from my brother's iphone 11 that can be plugged into the charging port, although, it doesn't work. the phone doesn't detect the earphones, so if i play any audio or something out of it, it just comes out of the speakers. it doesn't say either that it might not be supported, as it sometimes does when i plug an iphone cable or usb cable to another device except when used for charging normally.

is it the phone's problem or are the earphones just incompatible? the only issue that my phone has is its microphone. it doesn't work. is this somehow related to the earphones not being detected? wireless devices work, though, particularly wireless earphones or headphones.

any form of help is welcome! thank you so much :)))

​[Re-Titled by Moderator]