Yes you can use Pine Sol to clean a bathtub and it will clean and disinfect the bathtub and leave the bathtub smelling good.
Just mix some Pine Sol with water and then clean the bathtub like normal.
You can also use regular soap to clean a bathtub or even bleach to clean a bathtub.
If you use bleach to clean a bathtub then make sure to have proper ventilation and never mix ammonia with bleach because it creates a deadly gas.
You can also use Pine Sol to clean a toilet, counters, tables, hardwood floors etc.
Pine Sol is a disinfectant as well as a great cleaning solution.