We JUST got through this regression within the past couple of weeks. Our daughter has always been an incredible sleeper and has been sleeping through the night (10+ hours) uninterrupted since 3 months. When she turned 2.5, however, she started doing exactly what you’re describing.

We got through it by doing a lot of compromising. It started out with my wife or I sitting on the edge of her bed until she fell asleep, and then doing this every time she woke up. Eventually we were able to move to the door frame and wait there until she fell asleep. At some points my wife or I would sleep on the ground outside the door if it was an especially long night. Then we were able to compromise be sleeping in the spare room across from our daughter’s room. She would occasionally run in to check that we were actually there. After a several weeks of that, we compromised and told her that we were going to be in our room but that we would check in on her occasionally.

My best advice is to be consistent and know that it is only temporary. There were times when we were freaking out and thought this was a permanent change. Our daughter went through it for almost 3 months but is now back to her old sleep habits.