Hey there, hi there Robert!
Thanks for stopping by
planDisney with your question. Sounds like a stroll down Main Street U.S.A. is in your future, lucky you!
Based on your question I'm sure you already know this, but to visit
Magic Kingdom you'll need to have both a valid admission (your single park ticket) AND a
theme park reservation for the day you plan to go. Once those are in place, you are ready for your day of fun!
As much as I love all of the parks at
Walt Disney World, whenever I try to stay in one of the parks from opening to closing, I end up tired and cranky. I have a much better time if I take a break from the parks at some point to rest and recharge. So, the answer to your question is yes, you can absolutely leave Magic Kingdom at any point during the day and return later. If you're staying nearby at a
Walt Disney World Resort Hotel, I recommend going back to your resort to nap or swim, then head back to the parks for dinner, some more attractions, and
Disney Enchantment.
If going all the way back to your resort isn't practical, maybe just head to one of the monorail resorts for a change of scenery and a late lunch or early dinner. It's amazing how just sitting for a table service meal can recharge your batteries. We recently went to the
Grand Floridian Cafe for lunch on one of our Magic Kingdom days, and the monorail ride, comparatively peaceful resort lobby, and a leisurely brunch, did wonders for restoring our energy.
Hope this helps. Have a magical vacation!
Diane