Hello _megwol,
Thank you for using Apple Support Communities. Based on your post, you can't enable Bluetooth on your iPhone X. We'll do our best to assist.
It sounds like you've taken the right steps to troubleshoot this.
Have you tried to update to the latest iOS 15 version to test this further? If not, we'd recommend to backup your iPhone and get up to date: Update your iPhone, iPad, or iPod touch
Once updated, Restart your iPhone
Should the issue persist, then you'd want to bring in the iPhone X to a local service center for an inspection: iPhone Repair and Service
Get ready for your visit: Get your iPhone, iPad, or iPod touch ready for service
Select your region here and search nearby for appointments here: Find Locations
Due to the current conditions around the world, some stores may have limited hours or appointment times. They also may require specific things to visit them (Such as, scheduling an appointment, wearing a mask, calling to check-in, etc.).
Hoping this helps out, take care.