Yes it is too old --too old processor, no TPM, no drivers. See - Dell computers tested for upgrade to Windows 11 | Dell US The only 2 XPS desktops that will get Win 11-- XPS 8940 and XPS 8930 Windows 10 will be supported until 2025.  
I currently have an older 2013 XPS desktop computer XPS 8700 with processor Intel Core i7-4790 CPU @ 3.60GHz 3.60 GHz. I am trying to look for the PPT in the BISO but not able to see it. I went all over the place in the BIOS setting under Security and Advanced. No such option to turn ON. Meanwhile, my desktop is able to support bitlocker. Can someone please let me know if my current desktop is not able to support Windows 11 due to some lacking of this security feature? Is it my processor chip is too old and not able to support Windows 11? Any information will be greatly appreciated.
XPS 8700, PTT for Windows 11