Xiaomi Qin f21 pro seems to be a "dumbphone", it runs a simplified version of Android from what I can gather. I think the question that's being asked is how to install a different version of Android @Postspurs?
I expect this would probably not be possible without invalidating the warranty. Although we do stock some Xiaomis, we don't seem to range this one, so I can't really give specific advice about it. If the preinstalled OS isn't what you're looking for, then you may want to look into the seller's returns policy.
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