Beer belly

[rich2005]

This is one with no set rules, it will come with practise. My try at it, I lightened the image a bit to make it easier to see.

   

Split it into two stages.

1. Use the heal tool with a suitable brush to 'paint-out' the creases in the pullover. https://docs.gimp.org/2.10/en/gimp-tool-heal.html

2. Use the warp tool  to 'push' the pixels around and make the torso 'slimmer' https://docs.gimp.org/2.10/en/gimp-tool-warp.html

Only takes a minute, that example as an animation: https://i.imgur.com/lKQ0drI.mp4