Windows scales icons based on the user's "DPI (Dots Per Inch) Scaling" settings. While standard 100% scaling uses smaller icons, users with 4K or high-resolution monitors often scale their display to 150% or 200%, requiring larger source images to prevent blurriness.

For developers:

: The maximum standard size, essential for high-DPI displays and large icon views. Why ICO Files Contain Multiple Sizes

If you are designing an icon for a Windows application, follow these guidelines: