The mbr2gpt command in windows 10 converts it to UEFI. There's some prerequisites. It was one of the things I had to do to get Windows 11 installed on my PC on the beta channel a while back.A while back I used some partition utility (paid but had trial version) to change Win boot mode from legacy to UEFI.
You could probably try that with diskpart and convert gpt but I don't think that will work.
