Soundbars typically come compact, with two or more speakers built into the bar itself. In addition, there is often a wireless subwoofer. As a result, soundbars can improve your sound quality compared to built-in television speakers.

Depends. Every situation is different. Purely based on the quality of sound, a surround system, although more costly, will provide a much better movie experience than most soundbars.

If cost is a significant factor,  soundbars are a great alternative to improve your tv watching experience.

Note: Some soundbars rival the cost of entry-level surround sound systems.

Depends. If the room is capable of being completely dark, a projector is an excellent option. Projectors can project larger images than most television sizes. Note: projectors could require a bulb replacement after a certain amount of hours of watching it.

Suppose your room has a lot of light and can't achieve dark, then a large television is excellent.  Televisions are relatively durable but won't commonly display a picture size that a projector can.

Listening to music with high fidelity can be achieved with soundbars, home audio speakers, or even networked speakers such as Sonos or Heos.

A standard rule of thumb for selecting a projector screen size is measuring how far the seating will be away from the screen and dividing it by 2. (If your seating area is 200" from the screen, then a screen size of 100" is a comfortable size for viewing.)