Yes, the final price will change automatically. For example: if you set formula to x+5
(e.g. in “WooCommerce > Settings > Product Price by Formula > Default Formula” for all products), then the price for each product will be calculated by adding 5 to its standard price. So, for example, if product A has standard price (i.e. price that is set normally, without our plugin) at 100, then its new (i.e. calculated by our plugin) price will be 100+5=105, and if product B has standard price set to 50, then its new price will be 50+5=55. So if you change standard price for some product, then new price will be re-calculated automatically.
Hope that makes sense.