Hi there. There was a thread here on Hometalk about the same thing. Perhaps there are some answers that will help you there. There is a picture. https://www.hometalk.com/7868324/q-how-to-fix-gaps-in-wood-panelling
Do you mean gaps where two panels meet or the grooves in the paneling? Do you plan to leave the paneling as is or paint it?
If you're going to be painting it... Here is a post I wrote featuring painting tips, with a large section on caulking. To caulk the gaps in the paneling is a game changer with how good it looks afterward.
Here is an article that may help https://www.hometalk.com/7868324/q-how-to-fix-gaps-in-wood-panelling