The CPU upgrade would require replacing the entire system board (the CPU is soldered to the board, so it's not separately replaceable).  The GPU is also soldered to the system board, but the AMD Radeon GPU is the only one available, regardless of the CPU. You'd be looking at a minimum of a few hundred dollars for the board for very little CPU gain.  The funds would likely be better spent on a new system.  
I have a Inspiron 15 5570 with core I5 8250U and i want to upgrade to an i7  I also wish to upgrade my AMD RADEON graphics to an RTX 3060 or similar Do you know if that is possible thanks,
Inspiron 15 5570 upgrade in GPU and processor