It sounds like the general consensus here is that you're going to need to replace the charging port. The good news is that it's a pretty simple procedure for your phone, and the fact that the charging port is mounted on a separate board makes it inexpensive and easy. Here's a video showing you the steps needed to do the job on your phone.
[link|https://www.youtube.com/watch?v=TVJN4FYk2t8|Samsung Galaxy A12 Charging Port Replacement|new_window=true]
You can find the replacement board on most of the big websites like Amazon, eBay and AliExpress; pick whichever one works for you or do a general internet search for one local to your country. Here's an example that came up on a cursory search I did.
[link|https://www.amazon.com/Samsung-SM-A125F-Replacement-Charging-Connector/dp/B08Z469ZMM|Amazon.com: fonefunshop for Samsung Galaxy A12 SM-A125F Replacement USB Charging Port Flex Connector : Cell Phones & Accessories|new_window=true]
Good luck; let us know what you find and how it all turns out!