Do I need to play The Witcher 1 and 2 before 3 to fully enjoy it?

Yes and no. Any one who says no more then likely never played the first 2. All 3 games are based on the same story line in order. That's like saying would it be alright if I started watching the hobbit on the 3rd and final movie.

You will understand the game due to wht the story is about but you will have 0 knowledge of anything that has happened thus far. Or who anyone is really until the story goes on. You'll miss out on content about characters that they don't say in Witcher 3.

I don't think you'll personally lose out on anything by not playing the first 2 games. But each game progresses the overall storyline.

To enjoy it to the absolute maximum previous understanding of the narrative helps although it is in no way necessary to greatly enjoy the game. There are references to the other games which people who played the previous games will appreciate but the story itself is purely understood from The Witcher 3.

Witcher is story based so it will be best to go in order to Get the true feel of witcher 3