How to Note Then-Current Year in a History Document?

If I’m writing an historical work, is there a way for me to note the then-current year in the header? It would essentially have to be a header that can be batch-changed or on an individual basis, not automatically increasing at a flat rate. I’ve included an example of what I am attempting to reference (the date can be seen in the upper-right corner).

On a related note, these types of books will mark a new year in the margins, I am also curious if there is a way to do this, apologies if any of this is obvious and thank you in advance!

Maybe? You can use the current section title in the header, so this could work if the current section is titled with the year and then you use the parent folder title for the main header.

No, putting the year in the margin is not possible. That’s the kind of advanced layout task that Scrivener leaves to dedicated software.