FOR EDUCATIONAL PURPOSE ONLY, CHANGING IMEI IS ILLEGAL IN MOST COUNTRIES, MAKE SURE YOU CONVINCE YOUR ACTIONS BEFORE DOING THIS.
I DON'T RESPONSIBLE IF YOUR DEVICE IS BROKEN OR THE IMEI IS NOT CHANGED CAUSED BY YOU DIDN'T FOLLOW THE STEPS CAREFULLY OR HAVING A DIFFERENT EFS PARTITION SCHEME.
This guide was tested on Google Pixel 3, different device may also have a different EFS partition scheme, please make sure you adjust it with this guide. Other Google Pixel devices may use this guide without adjusting.