Are these the screws to hold windshield trim clips on a fish?

sadly those are special screws . That's why a package of clips contains the screws I guess. Anyway the screws shank and thread are #8 sheet metal type but the screws head is the diameter for standard #6 sheet metal screws. So If the car body already has holes for the #8 screw you'll have to have the correct special screws. The larger standard head of a #8 screw wouldn't allow enough space inside the clip for the trim to get in there with it.
If the car body doesn't have screw holes already, standard #6 sheet metal screws will work. Just drill a smaller pilot hole. Hope all that makes sense.