Hey there Marie,
Welcome to planDisney and thank you so much for your question! I'm happy to hear that you're planning a trip to the Happiest Place on Earth with your little one.
To enter one of the parks of the Disneyland Resort, Guests 3 and older do need to have a
theme park ticket and
theme park reservation for each day they plan to visit. There is a ticket option for Guests aged 3-9 and another for Guests aged 10+ though there is no proof of age required at the entry gate when you arrive at the Disneyland Resort.
Since you're visiting with an almost 3-year-old, I would highly recommend spending a lot of time in
Fantasyland and
Mickey's Toontown! There are so many fun things to explore and do specifically in both of these lands that your daughter will absolutely love.
Additionally, you can check the
Attractions page to see what rides she will be able to ride based on her height (just check the filter options near the top of that page). Additionally, if you're visiting with a group then the
Rider Switch service might be helpful if there are some attractions you'd like to experience but your daughter might be too young to enjoy quite yet.
Finally, make sure to take full advantage of the
Baby Care Centers - they're just as helpful for toddlers as well! It's a quiet spot to take a quick break to enjoy a snack, use toddler-sized toilets, or purchase something that you might have forgotten from one of the vending machines.
Thanks again for your question, Marie! I hope you enjoy your visit to the Disneyland Resort.
Have a Magical Day,
Greg