You should be able to use any soundbar that has an input to match the audio output of the Sharp TV.
If your TV supports ARC (not likely in a set that old) then get a soundbar that connects to the TV with HDMI. It will likely allow you to control the soundbar volume with the TV remote if CEC is turned on in the TV menu. Other audio outputs can't do that.
Digital audio outputs are usually better than analog but you use what you got. Check the TV audio menu to see if you can choose the type of audio output (bitstream or PCM). If you get a 2.0 or 2.1 soundbar either will probably work. If you get a 5.1 soundbar you need bitstream.