Hey there Cheryl!
I am so excited that you stopped by planDisney. I am a huge fan of park hop 'til you drop, so it makes me so happy to say the answer to your question is yes! You can absolutely add
the Park Hopper option to a single day ticket.
You can start your day off by having a coffee on Main Street, U.S.A. at
Magic Kingdom Park and end the evening watching the new nighttime spectacular,
Harmonious in
EPCOT. Or you could enjoy a morning safari in
Disney's Animal Kingdom followed by a visit to a galaxy far far away in
Star Wars: Galaxy's Edge located in
Disney's Hollywood Studios. The possibilities are endless. And if you're feeling extra magical, you can even visit all four theme parks in one day.
Before you start park hopping, it is important to note that a valid theme park reservation is required. Park hopping can begin anytime after 2 PM. You must start your day at the theme park where you made the original reservation. If a select theme park reaches full capacity, you will not be able to hop to that location. I recommend using the My Disney Experience app to stay up to date on any capacity restrictions.
I hope you are able to hop over to the magic real soon, Cheryl!
Tammy