Yes, your plants will need C02 to grow, in basic terms...the more you supply the faster they will grow.
However you don't necessarily need to inject additional CO2 via a pressurised system as there will be a certain amount of available CO2 in the tank water.
Low tech tanks rely on obtaining the CO2 from the atmosphere or decomposing substrates & other basic natural methods.
High Tech tanks rely on using liquid carbon or injected Co2....both types of set up can work but one offers very slow growth & the other very fast growth!