If you decide to take your own stroller to the park you need to make sure that it is no larger than 31” x 52”.
You can currently rent a single stroller at Disneyland for $18 per day, or a double stroller for $36 per single day.
These strollers are not known to be particularly comfortable, because they are made of hard plastic and they don’t recline if your child may want to nap in the stroller.
You can rent a stroller, and other baby gear, and have it delivered to your hotel for you to use during your stay. These strollers are not rented from Disneyland or the resorts, but from rental companies that operate in the area.
Disneyland is a big place, and that means a LOT of walking for little legs. Having a stroller means that your kiddo has a place to sit, rest, and reboot if they become overstimulated.