If you want to stop slicing, you need to stop slashing across the ball and it can all start with your backswing.
Another one of the most common faults that cause a slice is slashing across the ball because you haven’t fully completed your backswing or you haven’t started your backswing properly. There is a lack of stored power so the only realistic way to generate any power is to slash at the ball. This creates a lot of inconsistencies in both accuracy and distance.
A simple drill you can perform on the range (even on the course if you want) is to push a ball away with your club during the takeaway. This should help you develop a one piece takeaway to help complete your backswing.