Anal External Sphincter Stretching + Kegels, will make you remain tight?

I’ve heard from people that have been fisting for years that their asshole have gotten permanently loose…
I’ve also heard of people being able to take huge cocks but still have a tight hole…

I was wondering what the difference was and I was wondering if it’s possible to train your external anal sphincter to stretch during sex but then do kegels to tighten it up. Because at the end of the day it’s a muscle. The external anal sphincter is a muscle, meaning it can be trained. I’ve seen that kegels train your pelvic floor including your sphincter. So wouldn’t you be able to stretch it like you can do with any other muscle, but still be able to have it tight whenever you need throughout the day.

Am I missing something or is it possible to train your girth/diameter tolerance while still being tight through kegel exercises?