Usually, icon files contain three sizes at the same time:
When the viewing mode is tiled, it is 48 x 48.
When the viewing mode is icon, it is 32 x 32.
When viewing mode is list, it is 16 x 16.
I tried128 *128 64 * 64 48 * 48 32 * 3216 *16 respectively.
Obviously, the first icon is the clearest (use 48*48).
The second one is 128* 128. The bigger the size, the clearer it is, and there are many jagged shapes. It depends.