You don't need to tape body lines and curves . There are some rare exceptions to this but most cars you don't. It gets a little more complicated with rare cars and exotics that have sharp irregular lines. Mostly you need to tape around trim (plastic or painted). Some spoilers need to be taped so you don't burn an edge. Some door handles...
Just use common sense. If it looks fragile or really exposed to the edge of a pad, tape it.
DA polishers pose almost no risk of burning paint. Microfiber pads being a slight exception. They are more aggressive and the edges can be sharp