Tag iTunes song as most popular in album

Is there a way to add the star in front of the track number to indicate that it's the most popular song in the album (as shown in the picture below)?

The ID3 standard notes the track field as being numeric plus the slash for the total number.
So adding the asterisk would break the standard. But you don't necessarily have to comply with the standard if you have a player that supports it.
I think you can modify the track field in mp3 files but I am not sure about mp4 ones as they don't even allow padding zeros in front.

Where do you want to see this star? In Mp3tag? In iTunes? On your car mp3 player?

If you see this * in front of track #6 you should have a look at the same song in Mp3tag and press ALT + T to see the Extended Tags.
If you can show us a printscreen from this window for this song, we can see which tag you have to fill.

Unfortunately, this is not an existing tag on Mp3Tag. The star only pops-up for m4a songs with iTunes database. It is visible when you sync it to Apple Music only.