You are in charge here, not your child.
If child is messing around and trying to play at bedtime, then ahesnot requiring you there for reassurance. It's just a power game - procrastinating instead of lying silently and still to go to sleep.
It sounds like she needs much firmer boundaries at bedtime with higher expectations of her behaviour.
Your expectations for her behaviour should be that she lies down in bed, stays still and stays silent on her own. You can't make her sleep, but you can insist she is still and silent (until bored enough to relax and go to sleep).
You won't get there 'just like that', it will take some work. I would do Rapid Return. Develop a mantra you say: "sleep time now, we lie down quietly to sleep. Nan night" (or whatever). Every time she gets up, back in, repeat mantra, leave and close door.
Set her expectations earlier in the day, plenty of warnibg of what will be happening at night.
Expect her to treat it like a game at first. Just remain repetitive, boring and utterly consistant - back to bed, repeat mantra, leave. All. The. Time.
It may well start as a battle of wills. You have to show her that you are willing to dig your heels in more than she Is. Because you are in charge, she is not.