There are a few indoor playgrounds in LA that kids love. You want somewhere safe, clean, and engaging for a 4-year-old. I found a helpful guide at https://funplayworld.com/blog/indoor-playground-near-me-in-los-angeles that talks about a great spot with lots of activities. It’s well-maintained and perfect for weekend fun. They also offer memberships and party packages, which is handy if you plan to visit often or celebrate a birthday there.