Here's the link about locker rental, but I'm copying and pasting in case the Disney world website goes down and the link doesn't work:
https://disneyworld.disney.go.com/guest-services/locker-rentals/
Theme Parks and Water Parks
Multi-use, key-operated lockers can be opened and closed as often as you like.
A $5 refundable deposit is required for the locker key. Keys must be turned
in within an hour of park closing.
Large
17.5"h x 12"w x 16" deep
$9 per day
Small
11"h x 9"w x 16" deep
$7 per day
Multi-Park Locker Rentals
When visiting more than one park per day, simply return your locker key to receive your original $5 deposit. Then, present your receipt (plus the deposit) at the second theme park to gain access to another locker for the remainder of the day at no additional cost.
Epcot, Disneys Hollywood Studios and Disneys Animal Kingdom Park
Single-use, coin-operated lockers are located near Epcot, Disneys Animal Kingdom Park and Disney's Hollywood Studios bus Information booths. The cost is one dollar. Quarters must be inserted each time the locker is locked.
Additionally, larger-sized luggage lockers (23"h x 16"w x 29" deep) are also available for rent outside the Main Gate of Epcot.
Resort Hotels and the Downtown Disney Area
Single-use lockers are coin-operated and can be used only once. An additional fee is required every time a locker is locked. Resort hotel lockers are usually located near the main pool.
Small
11"h x 9"w x 16" deep
$7/day
There are no lockers at Disneys BoardWalk Resort.
Complimentary Lockers
Lockers are complimentary at Disneys Old Key West Resort, Disneys Polynesian Resort and Disneys Grand Floridian Resort & Spa. Your Key to the World card is required.
[It doesn't mention the Magic Kingdom, but I think that's because this is from the Magic Kingdom page, and the names of the other parks are actually links.]