PCIe line

[JohnHannabi]

Hi guys,
I'm looking forward to know something about PCIe Line. We all know PCIe Line which has five types, x1,x2,x4,x8,x16. As an assumption, i choose  a device that supports pcie 4.0 with x8, and then if i want to use only one of the eight lane to transmit data and rest of the seven lanes to be idle, emmmm, can i do this assumption or can i really control one of the lane to operate what i want?