In the most non-spoilery terms I can think of, episode 25 and 26 of the NGE anime take place inside, and the “End of Evangelion” movie is basically the same two episodes, but taken place outside. So, after watching the anime, watch the movie; it’ll make a hell of a lot more sense.
The “Rebuild of Evangelion” is a series of four movies, which literally rebuilds the original anime. A more fleshed out version of the story, a quote, “adjusted remake”. You don’t need to have seen the anime or “End of Evangelion” to watch these. Three of the four movies have been released, and the fourth’s release date has yet to be announced.
Some links may break, so message me if that happens, and I’ll fix them. Also, if anyone has a high quality link for Eva 3.0, please message me it so I can add it on.
Subbed links leading to Youtube, turn on captions to see the subtitles.