Is there any spoilers for me in "Spider-Man: Far from home" if I haven't watched Avengers Endgame yet?

Yes, there are a lot of spoilers that you will know if you have not watched End Game yet. It is possible that you have already seen some details online but if you still do not believe all of the details, then it is best that you will watch End Game first so that you will not be surprised with the new type of world that Spiderman will leave in.

Spiderman Far From Home is being marketed as the epilogue after End Game which means that it will show how people live after all of the things in End Game has occurred. If you would like to know what will happen in End Game then you should watch the movie first before watching this movie.