Soil should be 6.5. But, that's more about the starting PH. Soil has more buffers than your nutrient mix, so it will pull the nutrient mix towards its ph more than the nutrient ph will pull the soil. There are some caveats to this. If you overfeed (higher PPMs than necessary) the nutrient solution will have more power to pull the soil. Over time it could have an effect. Or, if your nutrient solution is extremely low, that might have a longer-term consequence. But, if you're in the 6.0-7.0 range, and not overfeeding, that should be good.
If you're new to growing it wouldn't hurt to ph to 6.3-6.8 to be cautious. For example, you probably dont' know if you overfeed. That's something you learn if you encounter salt buildup which results in nute lockout in early flower. You want to get to the point you don't get salt accumulation. When you're there, the ph of your nutrient solution will matter less.