Update bathtub and tile shower surround
A photo would help. The old material should be removed. Close and tape over the drain so nothing gets in the drain and clog it. Put cardboard or other protection in the tube to protect from damage. New material can be attached to make the surround. Tile, plastic liners, or whatever you want. Ensure all is water tight.
When you R&R the old, look for & repair water damage.
That is also the time to upgrade and repair any of the old plumbing.
There is tile kit paint you can use , check with your hardware stores
Or u can chalk paint it
This might work for your tub: https://thehoneycombhome.com/transform-your-bathroom-with-sink-paint/