Iron man suit was made but it wasn’t proportional to human size and hence can’t be used for all shoots. They employed the motion capture tech. Ocassionally Robert Downey would wear sleeves or helmet or chest plate and the rest was CGI.
In some cases he did wear upper body half.
There’s was a suit made, but in most of the suit action scenes the suit is CGI.
You might not like this:
But that’s the reality 😛