To determine whether your PC is using BIOS or EFI/UEFI please follow the steps below:
1. Press Win + R > type msinfo32 and press Enter.
2. Look for the BIOS Mode entry.
3. If the value listed is Legacy, then the Boot Environment is BIOS, otherwise the respective Boot Environment will be listed.
Access the disk management, and then check whether there is a EFI system partition: