Yes, always. You have LITERALLY 16 PCIe lanes connected to the connector.
Also, you should have Googled this.
If you're looking to do something like split a 16x card slot into 4x4, or 2x8 though - you need a feature called PCI bifurcation, in order to use any of those splitter/riser cards that split out the lanes.
If your chipset supports PCIe Bifurcation, you can do things like buy those 4x NVME adapter cards and run them all completely full speed; directly attached to the CPU.