Does any PCIe slot support NVMe SSD's automatically or do I need

What is the difference between PCIe Gen 3 and PCIe Gen 4? can i use gen 4 ssd on gen 3 slot 2 Slot is from the Ryzen 7 5700G then it will only support PCIe Found this tech site that explains that a Motherboard can have both PCIe and slots: can you tell when a slot machine will hit First of all, I know that a PCIe 4 SSD NVMe will be running at gen 3 speeds and bottlenecked by the PCIe 3 slot But I'm wondering if there are

canyonlands slot canyons It's hard to find PCIe NVMe drives that can cap the write speed of Thunderbolt NVMe enclosure Or maybe all my PCIe NVMe drives are old