If your PC seems to meet the minimum Windows 11 requirements but doesn’t have TPM, you may be able to turn TPM on if your processor supports it.
Here’s how to turn on TPM. The method will vary based on your device and it’s particular settings, but this is a good general guide.
Open Settings, then select Update & Security. From there click on Recovery and choose Restart now.
Then select Troubleshoot followed by Advanced options then UEFI Firmware Settings and Restart.
You’ll find the TPM settings (if available) in sub-menu in the UEFI BIOS labeled Advanced, Security, or Trusted Computing.
The option to enable the TPM may be labeled Security Device, Security Device Support, TPM State, AMD fTPM switch, AMD PSP fTPM, Intel PTT,or Intel Platform Trust Technology. You’ll want to check with your device manufacturer’s exact instructions.

Here are some links to instructions for major manufacturers.