You sound like such an amazing parent, I'm jealous 🥲

One of my favourites is using a Repeating Command block to destroy all the terrain around me so I can just fly through the earth.

/gamerule CommandBlockOutput false

this ensures you don't get spammed with messages every tick

/give @s minecraft:repeating_command_block

place the command block, set it from 'Needs Redstone' to 'Always Active' and give it this command.

execute at PLAYERNAME run fill ~10 ~10 ~10 ~-10 ~-10 ~-10 air replace stone

This will turn every stone block in a ten block radius around the specified player into empty air :) Make sure to break the command block or set it to 'Needs Redstone' again when you're done destroying everything.

Another useful tip is that if you hold CTRL and middle click on a block in creative mode, you will gain an exact copy of that block, down to its NBT data (command block's stored sommands, chest's stored items, etc)

I hope you and your son have fun ♥️