Thanks!
I'm not big on aging up characters unless it's somehow vital to the plot. Generally speaking, when I want to write about adult characters, I choose characters that are adults in canon.
Lisa certainly plays an important role in “Whoops,” which you might check out if you haven’t already. I haven't considered doing a story that focuses specifically on Lisa. I'm also trying to resist the temptation to over-use Lisa's mad science as a plot device. (Not that I'll never use it again; I just don't want to rely on it too much.)
I hadn't really thought about it, but now that you mention it, The Loud House does have a couple of adult female characters who are straight-up hotties (Ms. DiMartino and Nurse Patti). I'd certainly consider having Lincoln fool around with one or both of them. I also wouldn't rule out some incest action with his mom.
Thanks for the comments!