If you get This PC meets Windows 11 requirements with PC Health Check app, then you can use Windows 11 Installation Assistant which you can download from here:
https://www.microsoft.com/en-us/software-download/windows11
Alternatively, you can try manual upgrade using ISO file. Follow these steps:
- Download Windows 11 ISO from Microsoft website.
- Double click on it to mount it to a DVD drive.
- Then go to DVD drive, double click on setup.exe to proceed.
- Follow on-screen instructions to complete upgrade.
Let us know if this helps!