Caves & Cliffs should be automatically received as an update to the game, but some of the new features will not generate in areas of the world that already been explored, only new unexplored areas.
An easy way to check if Caves & Cliffs is active would be to dig down to where 'Bedrock' should be, it will have been replaced by Deepslate, and you will be allowed to dig down even deeper than before, hitting Bedrock once more at a much lower depth!
Hello
Newbie parent here! My son has seen many adverts for the new Caves & Cliffs edition but I can't find how to download it anywhere!
I have tried the Playstation store, the extension search part and even checked that he has the latest version which he does.
Hope someone can help!
Thanks in advance
Caves & Cliffs should be automatically received as an update to the game, but some of the new features will not generate in areas of the world that already been explored, only new unexplored areas.
should be, it will have been replaced by Deepslate, and you will be allowed to dig down even deeper than before, hitting Bedrock 
once more at a much lower depth! 
An easy way to check if Caves & Cliffs is active would be to dig down to where 'Bedrock'