Graphics card: DirectX 12 or later compatible, using WDDM 2.0 driver
8-bits per colour channel, high definition (720p) display, 9' or larger monitor
Download and run the PC Health Check programme to check for Windows 11 compatibility. It will discover specific compatibility issues that impede an upgrade.
Along with UEFI firmware (no traditional BIOS allowed) and Secure Boot, Windows 11 requires a hardware security component called a Trusted Platform Module (TPM). The GUID Partition Table (GPT) standard must be used to build up system discs as part of the UEFI requirement. The legacy Master Boot Record (MBR) system is no longer supported.
TPM 2.0 compatibility is incorporated into nearly every PC produced since 2015, albeit you may need to enable it in the firmware settings.