Can a PCIe graphics card work on a PCIe slot?

PCIe vs PCIe SSDs Benchmarked pcie 4 gpu in pcie 3 slot I used a Thermaltake PCIE riser last night, with GPU #3 in the PCIE3 slot and it worked but at PCIE 3 x4 …instead of x8, but after pcie x1 in x16 slot Or is it only devices connected to PCIe-3 slot that would impact speed of the PCIe-1 slot Thats how my GPU runs as I have 4 NVMe drives

pcie slot width It is a PCIe x 16 card A modern 12th generation motherboard will support PCIe x 16 Can he plug the PCIe x 16 graphics card into