Are you talking about the Night light settings?
If so go Settings, System, Display.
Also you can right click on the desktop nd pick Display settings.
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To help us to help you and to properly get answers to your post you should include some minimum information.
1. Device type. ie Desktop, Laptop, Tablet, Surface, Phone
2. Who made it and model, RAM size, HDD size. If home built what type motherboard, Intel, AMD, other
3. OS type, Home, Pro, Enterprise, 32 bit, 64 bit, etc
4. Current build. Hit the WIN key, type winver, hit Enter.