@vivieniberi, your phone is similar to many Android phones in that the recommended way to replace the screen is to buy it already mounted on the midframe, then you disassemble your existing phone and transfer all of the internal parts to the new screen+frame assembly. On an iPhone this would be a nearly impossible task, but on phones like yours it's relatively straight-forward. Sorry to say iFixit doesn't have a guide to that repair for you, but the French site SOSav has just what you need. It is, of course, written in French, but if you use it with a browser like Chrome that does translation, it is quite usable and their guides are generally well done.
[link|https://www.sosav.fr/guides/mobiles/xiaomi/redmi-note-12/bloc-ecran-redmi-note-12-4g#|Redmi Note 12 Screen Repair - Free Guide - SOSav.fr]