I have a 2018 5 doors polo and it has no rear speakers. is it possible to install rear speakers and connect them to the car's dashboard ? because when i go to speaker settings on my car and you can choose from which speaker you want the sound to come from , there is the possibility of only the front speakers
You can add an amplifier with front/rear speaker control.
In fact you could add tweeters, rear speakers, bass - all depends on your taste.
You might find this link to be useful...