The short answer is no. While resolution is definitely one of the most important factors in determining image quality via webcam, and a 4K feed is definitely noticeably sharper than even full HD video. That said, 4K can come with some issues that lower resolution cameras do not, like a major increase in bandwidth usage. Also, many of the devices and displays webcam footage is being outputted on (the majority of laptops, for instace), don't support 4K video anyway, so much of the increased fidelity is lost.