Because you have even lips, you can really have fun.
You can make them look bigger, smaller, rounder, etc.
For the most natural result we advise you to start lining the lips on the outer edges right on the edge and then the more towards the centre you are pulling the line, the more over the edge you can draw.
A general rule says that you can overdraw the upper lip by a millimetre and the lower lip by two millimetres and people won’t distinguish between your natural edge and the drawn edge.