For a pet to hatch with a visible trait, both parents need something in that trait slot, whether that's visible/visible, visible/carried, or carried/carried. Breeding two pets with visible/nothing in a trait slot will only ever result in a carried trait. So unfortunately, your lighs will always produce offspring with 4 carried traits.

Like Ender said, those two will always result in offspring with all 4 traits carried.

I can go into a bit more detail if you do want to breed for a 4 visible, because being able to breed 4 carried traits from the start would be a fantastic beginning to a project.

To have a chance at getting max traits visible, both parents need to have every trait carried - like the offspring of your two starting pets would. For a 4 trait theme, the odds of getting every trait visible when breeding all carried trait parents are then the same as getting 8 coins to land on heads in a row, since each parent would need to succeed the 50/50 check to pass on each of the 4 traits. I'm pretty sure that's 1/256, so not impossible, but not good.

The other issue is making sure you're able to breed pets with every trait carried that aren't too closely related. Like all breeding projects, you would need a minimum of 3 unrelated pets to start out to get enough combinations of unrelated pets in the 2nd generation onwards. That doesn't have to be a 3rd themed lighira you own, just one you're able to breed with.

This would be an absolute minimum 3 generation project, with the main bottleneck of getting a pet with all 4 traits carried that isn't a direct child of your two starting ones. Likely more generations, as going from breeding 4 carried traits to 3 carried and a visible ect, improves the odds a lot each time.