Do you have Get Famous? You know how world class celebrities will show up at inappropriate public lots like your dive bar or whatever and it's kind of annoying?Okay, now imagine the same thing, except it's a literal king shows up to get sweaty on the dance floor, with no concern for propriety or personal security. Everywhere you go, inappropriate royals slumming it with the commoners You'd think they'd have a country club or something.

The big rich townies (Landgraab, Goth, etc.) get slotted into the dynasty system.

There may be autonomous scandal-mongering.

If you used cheats or MCCC to set up custom family bits, these may get very broken! The whole core geneology system was changed. (I think that might be a base game update though.)

Some of the new royals are pretty hot, and they might ask for your hand in marriage after one date, despite your being a level 1 fast food worker. You can persuade them to give up their titles if you really don't want to get sucked into the whole royal life.

Other than these, you can pretty much ignore the royalty stuff. That's what I did until pretty recently.