I used Traveler to Change Hometown and move my sim into a new world. None of the lots that are added by different EPs are installed. Is there a way to trigger that so that I don't have to manually add festival lot, tattoo parlor, consignment shop, etc.?

I don't know if there is a way to trigger it after the fact, but if you don't mind reverting to a save before you moved it is possible to get this to happen beforehand.
If you make a new save in that world, you can select Yes on the prompt to place the auto-lots, save, exit, and copy the .nhd file from that save and drop it in the save folder you are currently playing. Then when you travel to that world for the first time, that is the copy that will load.

Oof. I appreciate the answer, but I've got a lot of playtime and relationships my sims have built up while they were on vacation in the world. I'll definitely remember this for the next time it comes up.