You have a 4K displa a small laptop 4K display it has a resolution like 300DPI Photoshop UI will be very small where if you have a large desktop 4K Display like a 32" or larger the display resolution will be in the 100DPI range and Photoshop UI will look normal. My Dell desktop 4K Display is a 24" Display its resolution is 185DPI Photoshop UI would be on the small size there However, I keep Photoshop UI on My other displays they have a 100DPI resolution. All I have on the 4K display is Photoshop Image window. Only the information in the Image windows frame is on the small side. If you only have a single display and it has a high DPI resolution Try using Photoshop CC 2x UI scaling Preference. You could update your Widows registry and add a manifest file for Photoshop and force Photoshop to use Windows scaling to use other scaling factors.
Thanks. I have a 16 inch display. Will implement your suggestions