If you have the trans in and the fluid level correct, or access to a car that has the same trans, and dip stick configuration, meaning length.

With the engine off pull the trans dip stick, wipe it dry, reinsert the stick. Pull it out and see how far up on the stick the fluid is. With the motor off and cold the level of the trans fluid rises, drains back from the torque converter is the reason that happens.

Using the dip stick and starting where it rest when seated in the tube, measure down to the fluid. Subtract an inch or so and cut the tube down that much.

With the same measurement, from the bottom or end of the stick come up that amount and cut the stick. Transfer the low and full markings to the modified dip stick.

Sounds confusing but really is not, shorten the tube from the top down. Shorten the dip stick from the bottom up the same amounts.