| An auto-box is designed to protect its self i.e. then using it as an engine brake it won’t change down until it can without damage as for using it as a manual that’s what the positions are there for. When you boot it hard the torque converter takes most of the hammer which is a fluid coupling and virtually indestructible. If you already had slip in the box then you finish it off, but if the box is good and oil/filter is change as it should be and you use a good AFT then you should be able to do what you like with the box that’s what it’s built for. | 
