PNGs much like other images like JPG can be used to create icons, or form whole icon packs like the ICNS format for Apple Mac OS X. Your best shot would be to use some of the dedicated icon editing and making software like IconWorkshop.
Convert Portable Network Graphic to Apple icon graphic format.
We have found one software suitable in our database for this conversion.
Apple macOS / Mac OS X software - convert png to icns on OS X
A basic document and image viewer in Mac OS X
Convert from png file format
|Yes, Preview supports icns file conversion as a target file type.||Yes||No||No||No||No||Yes||No|
The table with program actions contains information about what each program is capable of doing with their files. This may be a good pointer for further searches for certain file conversions and help you find the converter you are looking for if our search result is insufficient for you. However, it is far from perfect and may sometimes show results which are not really usable because of the nature of the software handles the files. So a conversion that appears as possible, just because of matched actions, may in fact not be possible.