I'm trying to force BitLocker to use AES-256 level encryption for the entire operating system drive on Windows 10 Pro. The drive is currently encrypted with BitLocker at AES-128 level encryption. I don't see anything online for how to do this. I've tried changing the group policy settings and decrypting/encrypting to no avail.
You have to first decrypt the drive than encrypt with AES-256. Unfortunately, this is the only solution.
It is also stated here: Change BitLocker Drive encryption to XTS-AES 256 during OSD with #ConfigMgr
This can be changed using a GPO or CIs in ConfigMgr but then you have first to decrypt the disk, assign the new policy and encrypt the disk again. This is annoying and not very user & admin friendly