You can’t really expect to sync physics over the network with 100% accuracy (probably true for any movement).
That said, the system is based on a pre-built function.
As long as you sync game time the two clients will solve the math the same way. It should also already be frame independent.
As far as water interaction, splashes etc. That’s done at a local level with vector fields and particles in fortnite. You should aim to do it the same way.