Have you ever noticed how lengthy most old books are? By old I'm speaking of volumes from early 1900's and, of course, the 1800's. I have a number of old books and I, unlike some people, read them. They are wordy, detailed and often delivered powerfully. They were written with great care, often taking years to complete. I say all this to try and make the point that those writers were used to spending the time to compile their stories and placed as much information as they desired in their novels.
On my recent post one commenter stated they are having difficulty writing longer pieces. I often say that it takes a lot of material to make a novel. And it does. When I write I sit down and meditate on the story, the characters, and the setting. As each bit of that story formulates in my mind I write it down and I slow my thinking process in order to put down all the details that create the scene I picture in my mind.
To avoid brevity: fill your mind with all the details of the scene you are writing and then put it down as it comes to you. Don't worry about the end of the story, don't force it, let the story flow with vivid detail that will bring it to life for your readers. Only when you settle your mind into the river of imagination, soaking in it, encouraging all ideas to blossom . . . Build it with care, with artful design, and then it will not suffer from brevity.