In the end, Trunks held a longer battle with Perfect Cell but did nothing to him. He was physically stronger yes. But his body had bulked to a point that it hindered his movement. So if Vegeta and Trunks decided to go toe to toe vegeta would have won.

DID Trunks defeat Cell?

Future Trunks destroys Android 17, Android 18, and Cell of his timeline, ending their reign of terror and finally bringing peace to the future.

Could Goku could have beaten Cell?

Simple as that. Later in the otherworld, Pikkon defeated Super Perfect Cell like he was nothing, and Goku and Pikkon were evenly matched when they were fighting in the otherworld tournament. So from that, Goku was able to defeat Cell. Even if Pikkon was slightly stronger than Goku, Cell was still no match for him.