Hertz goal is to ensure rentals leave with at least 75% charge. In practice that is not always the case. I picked up a Polestar at 20%.
For returns you are asked to return at 75% or whatever charge the car was at when picked up, whichever is lower. So if you picked up at 20% you can return at 20%. If you picked up at 85% you can return at 75%. If you return at the wrong state of charge you get charged $35.
They also have a $35 fee you can prepay that lets you return at anything above 10%. If you return at 70% or greater the $35 is refunded.
There is an extra fee of $25 if you return the car with less than 10% charge.
Level 2 chargers are not easy to come by at Disney. There are only a few and they fill up quickly. I have NEVER been able to get one. They are also not very well maintained. I don't ever plan my trip expecting to charge while at the parks or Disney Springs.
The Magic Kingdom chargers are rated a whopping 1.2 out of 10.
https://www.plugshare.com/location/89486
The other locations with level 2 chargers at the resort are not rated much better.
If you don't already own an EV, renting an EV on a vacation could be overwhelming, in my opinion.
If you rent a Tesla you could probably do all your charging at Tesla Supercharger stations. The charging gets billed back to Hertz and at some point Hertz bills it back to you, could be months before you see the charges billed to you. This would be relatively easy.
If you rent a non Tesla EV you will probably need to download several different apps to DCFC (equivalent of Tesla Supercharging). EV chargers typically don't let you just pay with a credit card but instead require you to use an app and have an account. Even if the charger has a credit card terminal there is a good chance it doesn't work. This would be more difficult than a Tesla.
For level 2 charging Hertz provides a J1772 adapter with each rental. The majority of public level 2 chargers are J1772 with some Tesla destination chargers. Hertz does not supply a Tesla destination charger adapter with non Tesla EV so non Tesla rentals can not use Tesla destination chargers.
I typically drive just 100-200 miles max during a week when renting a car for a Disney trip. In that case I should expect a single DCFC(Tesla Supercharger) session at the end of the trip as my only needed charging.
That session should last about 30-45 minutes to go from 10%-80%. The length of time depends on the power output of the station, weather, and battery temperature. Central Florida should not be a place where the weather and battery temp are limiting factors but it could add 5-10 minutes if unusually cold.