My 12 Pro Max fell in Public toilet.

You don't.

It's to late.

Any Bacteria has already gotten into the device and is multiplying like mad.

It will never be clean again.

Or just listen to Deggie or this Apple document:

Cleaning your iPhone - Apple Support

You could also get an UV phone sanitizer, I personally don't think they are a good idea but if it bothers you so much, worth a shot.

No, you will end up with it inside your iPhone combined with the toilet water that is already there. Set it aside in a cupboard for 4 to 5 days, charge it for 30 minutes and see if it still works. If it doesn’t click on the Get Support link at the top right of this page to start the service process.

Letting it dry that long should allow time for any germs to die.

IP68 is actually a pretty low water resistance rating and is done under strict laboratory conditions. Do note even with this rating Apple does not warrant the phone against water damage. And the test is done with temperature controlled water that is still and pure. It does not cover alcohol. I'm not sure you phone will survive the water incursion with the toilet so if you want to dip it into alcohol that is your choice but there are many things within the phone that don't mix well with alcohol. Good luck to you.