That’s a great question! Considering it’s been six months since the initial burst of power, I’d say their powers are growing in strength still, that is to say there is a potential of them getting stronger yet. But they’re also learning just how versatile they can be with their abilities so a little bit of both, really. It also comes down to how you want your character’s arc to develop. 

Maybe they were practicing nonstop for those six months after the initial burst and have a dominion over their abilities thats closer to mastery. It should serve your character’s narrative and the overarching narrative is built to accommodate that kind of player freedom. 

Hope that answered and your question!