The CPU is not upgradeable - it's a BGA processor, meaning that it's soldered to the system board. You would need to replace the entire system board, assuming one is available for your system model. It's likely a G7-15 7588 system - some of these shipped with i9 CPUs, but that upgrade is likely to stretch toward or over $1,000 just for a system board, without labor.  
Hello, I have a Dell G7 with processor Intel Core i7-8750H and I wish to upgrade it. Which processor can I install on this socket? My baseboard is a Dell 0PK2PP. Thanks in advance!
Processor upgrade on Dell G7