If there are no audio output on the TV you can use the audio outputs of any external sources.
Sometimes an HDMI input selector with audio extraction will work.
It's also possible to connect a speaker to line level converter to the wires going to the internal TV speakers. That provides an audio output that can connect to the aux input of a soundbar.
Not electrically complicated but you would have to open the TV and maybe drill a hole to get the wires out.