No. There isn't any 3rd party with a secret formula that lets them accurately predict if more people will be at MK vs Epcot on a certain day 3 months in the future. I also doubt Disney shares any of their internal metrics with 3rd parties. Even if someone has a reservation, it still says nothing about what time they might arrive or how long they plan to stay.
Parks tends to be busy most of the time, so best to plan accordingly. Before covid, Disney used to plan the various special events around times of the year things were slower to help fill up the hotels/parks and spread things around. There isn't anyone who knows how things will recover as more of covid is behind us, so projections based on historical data may not be very accurate.