Windows 10 Settings → Personalization → Background (should be where you landed on Personalization) → Color Filters → Use color filter: On (Optional: check box to select shortcut key) → grayscale (or other)
Windows 11 Settings → Accessibility → Color filters → Color filters: On → Grayscale (Optional: check box to select shortcut key)
Windows 10
Settings → Personalization → Background (should be where you landed on Personalization) → Color Filters → Use color filter: On (Optional: check box to select shortcut key) → grayscale (or other)
Windows 11
Settings → Accessibility → Color filters → Color filters: On → Grayscale (Optional: check box to select shortcut key)