You don’t ABSOLUTELY like, ABSOLUTELY need to see the previous, but to be informed and have a good understanding, “Infinity War” is what you should watch before Endgame. In endgame it contains Thor’s friend from his movie “Thor: Ragnarok” and in order to understand that relationship you have to watch his movie. In “Age Of Ultron” you will better understand Vision, and his relationship with Scarlet. And so on and therefore with the movies. All you need to see is really “Infinity War” or you may be a little confused. Even if you want you can watch Endgame first and then go back and watch “Infinity War” as it is on Netflix.
Thanks.