6 is a bit young, however it is an opportunity for you and the child to share an activity, at all times under your direct supervision. You would need to take the lead and teach the child responsible operations, safety and care.
Take a look at the DJI/Ryze Tello with a Gamesir T1d controller. They're easy to fly, designed for indoor use, and pretty resilient. This is the first step up from a cheap, hard to fly toy to an actual drone aircraft. ALWAYS under your direct supervision. Develop good, responsible operational habits and in just a few years moving up to a DJI Mini will be simple and reasonable.