Shifts hard from first to second and second to third

It would be best to flush the fluid because this is sure to get all the fluid out but this requires a flush machine. At the very least you will want to drop the pan and clean out the pan. This way you can see if there is any metal in the pan which is a sign of its health. I attached the process for dropping the pan which is something you can do in your driveway.

Then you will want to check for codes just to see if there is an issue there. If the fluid needs to be changed then I would start with this because it very well could fix this issue.