How to repair the phone which was fallen in water for more than 8 min

First of all DO NOT ATTEMPT TO TURN IT ON and if it's on SHUT IT OFF. If you are confident with repairs and if it was clearly malfunctioning before you shut it down then take it apart and disconnect the battery to prevent the phone from being further damaged. Can't find a disassembly guide rn but I'm sure there's Youtube videos about it. After that, remove the motherboard and clean it with isopropyl alcohol and a brush to remove any dirt or substances still on the motherboard. After that wipe it as dry as you can with tissue, and put the motherboard along with the rest of the phone somewhere with good airflow to allow get rid of the residue moisture. Give it about a week to dry, just to make sure all the parts have no water residues inside, then reassemble to test it. Of course, you can disassemble everything to make it dry faster but it'll get pretty complicated. keep in mind that you'll need a new battery since a wet battery could burst in flames.

My research shows that the A23 have no official IP68 ratings so there's a high chance there's water ingress. Even if you don't see anything wrong with it I still recommend doing what I said just to be safe.