So, If I keep the core at +250MHz, and its stable, and the card isn't overheating; it is healthy for my GPU and wont break it?
Yeah, that's fine. Increasing the clock speeds won't hurt the GPU, voltage is what can hurt a card. The 3060 is a locked down card, so you don't have voltage control. Because you can't overvolt the card there's no way to really break the card. It's fine.