So I bought a Asus GeForce RTZ 2070 super and a EVGA 650W b3 semi modular PSU. The GPU has two 8 pin connectors To connect to the PSU but the PSU has one wired 6+2 pin and 4 pin. Which won’t work since it’s missing two pins, it comes with another 6+2 and 4 pin cable. Can I use the 6+2 from each cable and not use the 4 pin part on each cable to plug in the GPU or will I need to buy another PSU?

A 6+2 pin PCIe/VGA connector works as either a 6 pin (with the 2 pin part left hanging) or an 8 pin connector (using the 2 pin part)..So, yeah.
 
It's actually recommended to use two separate PCIe/VGA cables sometimes (for performance and safety reasons) instead of one cable from the PSU that splits off into two PCIe/VGA connectors for the card.
 
Welcome to the forums, by the way..Be sure to read the Ultimate Self-Starter Thread For New Members if you haven't yet..Lots of good info there for you.