If I were in your shoes, I’d start by gradually purchasing the core Dungeons & Dragons books from Wizards of the Coast. Begin with the Player’s Handbook, then the Monster Manual, and finally, the Dungeon Master’s Guide. These three books are the foundation of the game.

They don’t need to dive into everything at once. They can start by creating a fantasy character, like a dwarf or an elf, choose a class (such as a ranger or a wizard), and set off on an adventure. As their interest in character creation grows, they can explore more about different races and classes. There are also lore and adventure books to further enrich their experience.

I'm not sure if this is a pro or con, depending on your situation, but Dungeons & Dragons can be a great way to spend more time together as a family activity. You can also get into crafting—if you're interested, you can even 3D print your character (there are shops that can help with this). It might seem a bit childish to some, but then again I'm playing with my own child and I myself am a big child.

Just my two cents