Toilet bowls not filling with enough water
The level of water in the bowl is fixed and depends only on the geometry of the S-bend that is part of the toilet

 

If you add one drop of water into the bowl, it will raise the level at the left side and one drop will fall down the waste pipe.

The only exceptions would be


installing the toilet on a slope would change the amount (but still fixed)
if the waste pipe is not at atmospheric pressure due to inadequate venting


water can be sucked out
excess pressure would push water back into the bowl (and there would be a flow of bubbles into the bowl)



None of which helps you. To get more water in the bowl you need a different design of toilet.

The syphonic action might mean that if the flow from the tank cuts off sharply, there might be room for more water. However the toilet is designed so that the flow from the tank continues, refilling the bowl completely, after the syphon has initially drawn out all the bowl's contents.