The individual visas expire after 5 years or when your passport expires - whichever is nearest.
So make sure you have at least 5 years left on your passport before getting any TE visa inserted because they only way you're getting another 5 year visa when it expires is at the airport on the way into the country or by going in person to Chaeng Wattana.
You don't need to go to Thailand at all, if the current visa expires while you're out of the country you can arrange for a new one to be inserted on arrival at the airport. You need to make an advance reservation for this or you won't get it by just turning up unannounced and it will be a pain because you will then need to go to Chaeng Wattana for a separate visa insertion.
Planning ahead you can easily avoid the above issues.
For the other guy who was told there is a paperwork requirement and he needs to get in touch with Thailand Elite to renew - this was the case during the covid pandemic period, suddenly out of nowhere you needed to have a special authorisation letter from Thailand Elite but they told me last Novemeber that this is no longer needed when I did my annual extension, however then then sent me a letter anyway which was a little odd but I printed it out and took it with me anyway.
Sounds like the immigration office were not aware of recent changes which were changed again and again over the last few years when it comes to TE.