You cannot upgrade the system to meet Windows 11 requirements -- though you can install Windows 11 without TPM/supported CPU (at least at present -- Microsoft has stated it may release updates that enforce the CPU and TPM requirements in the future). You can install either a 2.5" SATA SSD or a SATA (NOT NVMe) M.2 SSD.  
I have an Inspiron 5559 from 2016. I would like to upgrade the hardware to be able to update to Windows 11. Can someone please let me know what hardware I need to buy/replace to be able to do this? Also, do you know if I can switch to an SSD hard drive? Many thanks in advance, sincerely, Joanie
How do I upgrade my Inspiron 5559 to use Windows 11?