Does gpt support legacy boot

No. The GPT partition table does not support legacy BIOS booting, only UEFI (UnifiedExtensibleFirmwareInterface) booting. The traditional BIOS boot method uses the MBR partition table, which stores the bootloader in the MBR sector of the hard disk, and when the computer boots up, it first reads the bootloader in the MBR sector and then loads the operating system. The GPT partition table stores the bootloader in a special EFI system partition (ESP), which requires a UEFI boot method to read the bootloader and load the operating system.