How to move or extend C drive to D drive without deleting.

How do I extend without deleting the contents of my D drive if its not possible, is there a way to at least transfer the contents of my C drive to my D drive because my C drive is full and its a hassle right now to delete anything. any convenient way to transfer, extend, or to make it so that i don't have to move everytime I install because it can also mess up directories I think and it's just really fkin annoying. Any suggestion is appreciated, thank you.