So while it’s possible its not an easy process!
We don’t have a guide for your exact system but this one is very close to the same procedure to get the logic board out iMac Intel 27" Retina 5K Display Logic Board Replacement Keep in mind you need to use the correct tools and technique to get the display off otherwise you risk damaging it!
After taking the logic board out getting the current CPU out is not that hard but putting the new one in as a real pain! Many people struggle getting the CPU properly placed in the socket and/or damage the logic board socket in the process.
Of the three systems I got in which someone had attempted to install a replacement CPU in this design series two had damaged to logic board to the point I couldn’t save it.
Also be careful on what TIM you use and don’t over do it! It takes very little to do the job.