Is there a specific regulation or Pamphlet that lists US Army Additional Duties and their requirements?

There's not one that lists all additional duties. But many regulations dictate additional duty NCO's and Officers for certain positions. You have Key Control, Motorcycle Safety, Victim Advocate, EEO, Resiliency, Master Fitness, Fire Control, and Retention NCO - each covered by a separate reg. That doesn't even begin to cover unit specific and MOS specific additional duty roles.

If there was one reg that had it all, it would have to be updated every time one of the 200+ additional duties were updated. Since it takes years to get a reg updated and reviewed, that would never work. That's why a lot of regs split into DA Pams and AR's, but still that would be a full time job to review 300 or so other regs for updates to additional duty personnel.

I found someone else asked a similar question on here when I Googled it:

https://www.rallypoint.com/answers/how-can-i-find-what-additional-duties-are-required-for-company-level-units

https://www.rallypoint.com/answers/where-do-i-find-information-regarding-additional-duties-or-appointed-duties

I'm not seeing anything that comes up in a specific regulation or DA Pam or anything.

As far as I know, there isn’t anything in writing except for what your specific duties are for your MOS & Rank. Additional duties are & always have been as needed, and as seen by senior personnel, to be delegated to subordinates.
I’ve seen E-5’s chipping paint, swabbing decks because it was needed & we were the lowest ranking at the time.