I only played W2 and W3. W2 was not necessary to play the third one, but it’s certainly not a bad game (I personally didn’t like it as much due to the fairly linear story telling). W1 I am told is not that great. Both are much shorter than the complete edition of Witcher 3 I’d argue. The DLC should be fine if added afterwards, I can wholeheartedly recommend both. Blood & Wine especially has received wide praise back then as “being a whole game in the shape of a DLC” .

Thronebreaker is a tales-game that I haven’t had the time for yet. I was told it’s solid.

The Witcher Adventure Game is essentially a board game and is absolutely not necessary for any of the other games. If you like board games and have people to play it with, it’s actually quite good. It has a bit of a learning curve and I very much recommend reading or watching whatever tutorial you can grab a hold of, because it is not all that intuitive.