OK, in that case tackling this at bedtime will ultimately help in the middle of the night too (and daytime naps).
She needs to be able to see you and you need to be able to see her. You say she gets out of bed to make sure you're there. So be in her direct eyeline so that she can see you from her bed, as she is lying down. It's fine is that means sitting/standing in her room or by the bed, don't feel you need to be out of her room - you dont.
For whatever reason, she's not feeling content and secure in her room when going to sleep and your presence is the security she needs. You need to go through a process of giving her the support she needs, then gradually weaning her off needing it so she can feel more secure on her own.
Not unusual for this type of night time insecurity to develop around this age, so it's nothing unusual or anything youve done. Just emotional development.
She's got to trust that you'll stay with her until she is asleep. If she thinks that you are going to sneak away as soon as she relaxes, she will force herself to stay awake specifically in order to make sure you stay (and keep her safe).
So always, always, ALWAYS, stay until she's fully asleep. Every night, every wake up, every time. And until she learns to trust that you'll do this, be where she can see you at just a glance as her head is on the pillow. Once she trusts you'll stay, she'll be less inclined to check and and you can then start the process of moving slightly further away each few days.
As for now, be where she can see you as she lies down. Then develop a mantra of expectations and a settling routine. I would suggest: "It's sleep time now, we lie down quietly to go to sleep. Nan night".
Because you're watching her, you can spot any movement before she gets close to getting up. So don't let her get up. Any sitting up - repeat mantra and have her lie back down. If she doesn't, repeat your settling routine. For example as she's sat in bed give a big cuddle, kiss, say mantra, reassure you will not leave and she can see you, say mantra, wait where she cam see you.
Once all this is established, it's a case of being a broken record about it. Keep her in bed, respond to her super quickly (including any night wake ups) and be persistant and patient.
Once she's settling more quickly with you in her eyeline, give it at least a week without changing anything to establish this (and remember to always stay until asleep). Then move a step away from her, but still in eyeline, or partial eyeline. Still stay until asleep. Give that 3-7 days and then move a bit further away. Give that a few days and move to doorway eyc. With each change, still be on her like a hawk if she goes for getting out of bed and always stay until asleep.