Assuming you have gone to Windows updates and clicked on checked for updates, MS is rolling out the update in stages and many users have not received it yet. But you can install Windows 11 without waiting for the update to appear. Go to the Windows 11 download page here. Then you have some choices. You can either go with the Installation Assistant (first choice) which is the update version. Or you can click on the second choice which is the media creation tool for Windows 11. That will create a bootable installation flash drive. Either choice will install Windows 11.
My Latitude 5590 with i7-8650U passes Microsoft's Windows 11 compatibility checker. Why won't it offer to upgrade from Windows 10 to Windows 11? The BIOS says TPM 2.0 Security is both “On” and “Enabled”. The i7-8650U is in Microsoft's list of Windows 11 compatible CPUs.
Latitude 5590 won't offer to upgrade to Windows 11