suspected minor water damage causing ghost touch

The rice drying out an iPhone is honestly a wives tail. Meaning, it doesn't really work. If water got inside the phone, water damage cannot be repaired. The only solution for water damage is a replacement phone. It is not covered under warranty. It would qualify for a greatly reduced price replacement if the phone is covered under a valid AppleCare+ play, which you would have had to buy within 60 days of buying the phone originally.

Bottom line is you either need to buy an Out of Warranty replacement at about 60% of the cost of the phone when new. Or use your AppleCare+ plan if you have one. Or buy a newer iPhone and recycle your current phone as it is worthless in trade.

You would need to have it inspected to verify if there is indeed water damage. If there is...as mentioned, your options are pay for a replacement (either the out of warranty price or the AppleCare+ price if you have it). Resetting it may be something you have to do. You can do a full backup via a computer before resetting it so that you don’t lose your data. But it’s a basic step that would be suggested for any issue when Apple would troubleshoot.