Let her have all the loveys she wants, in her bed with her.
Let her choose the ones to have in bed.
Let her have a flashlight in bed with her and a sippy of water.
Sit, in the room, instead of laying with her.
At this age, they are still very young, but on the cusp of being a "big kid" but are still having cognitive and emotion based developmental feelings about it.
The world, expects them to be all big and grown up, because they are 3. But, they are not yet, fully all grown-up.
It is an age of dichotomy. Hence, 'growing pains' emotionally.
Hence, it being a hard age.
For the child.
Have a regular daily routine at night.
Tell her you will sit in her room, versus lying down with her.
As a compromise.
Then when she gets used to that, you can gradually leave the room.
When I was that age, I simply got scared at night. And missed my parents. In my room by myself. It is developmental. At this age they do developmentally begin to get night time 'fears' as well.
Lots going on in their little minds. Childhood.
They do grow out of it.
So you can do the cold turkey, or gradual transitioning for her.
Up to you.