I've seen some pretty unsavory parts of the Internet, where people doxx others for the lulz. The targets of these trolls do a lot to change run from them, like make brand new social media accounts, getting new phone numbers, etc etc, but if someone wants to try hard enough...they're going to find it. There is always a paper trail, digital or otherwise. To the trolls, it's a challenge to find this new info.
Now onto you. You write porn under a pen name, cool. Who is going to care enough to find out who you really are? Are your coworkers randomly going to think "I bet guppie wrights smut, I'm going to scour the Internet to find proof of this" ? If anything, it'll be the other way around. "I am morally outraged by what G. Uppie wrote in their smut, because I find hand holding exceptionally reprehensible, so I will find out who they really are."
You can do things to make it harder to make these connections. One is to have multiple separate online identities, where you never reuse phone numbers, emails, or user names across identities. You have your regular person name/info, and then you have your smut name/info. It's really tiring to manage multiple identities, so you have to decide what the risk is/how motivated your future enemies will be and decide that way. There's people from my past that I do not want to be able to find/contact me, which is part of why I also legally changed my last name, but it also means that I can't ever make a new Facebook, because friending the same people will cause Facebook to realize [old me] and [new me] is the same person, and then recommend [new me] to [bad people], but that's something I'm okay with giving up. I'm okay with having separate personal and professional online identities, though I know there's going to be some merging once I'm published, but again that's something I'm willing to risk. You gotta figure out what your limits are.