One of the hardest things for a new Lightroom user to work out how to perform is a simple image resizing. Look as hard as you like and there simply isn’t a resize menu command.
There is, of course, a way to resize images and it is done as you Export them from Lightroom which makes sense when you know how Lightroom works but if you’re a new user it’s just plain confusing.
So, here’s how to batch resize in Lightroom:
Select the Library module and select the images to export. Choose File > Export.