Stuck Lock Button after drop

It's definitely possible to try to fix this. but you'll need to get the phone open to do so. if the housing is the problem it may require swapping the housing to one that's free of bend depending on how significant the bend is.

Word of warning, the 12 series is a bit of a bear to get open due to the strength of the adhesive holding the screen in so you'll need a fair amount of targeted heat. And a lot of patience. You'll need to remove the battery and the logic board to get at the power button mechanism. You can see if you can bend the housing back out from the inside. Or at least make sure the power button itself it seated correctly.

Be aware if you have a 5G variant of the iPhone 12, there is an antenna soldered to the bottom of the logic board which goes up and around the battery which is really the only reason the board would need to come out since the antenna covers the screws necessary to get at the button. There isn't an iFixit Guide for either of these, but using the other Guides for reference is usually my tactic for handling this.

Some pictures of the damage may also help determine the best course of action since we don't know exactly what sort of bend you're dealing with.