I bought this "rubber tree" at Home Depot years ago. At least I think it's what we call a Rubber Tree. It's been growing tall but can't support its weight. One summer I brought it outside where the wind strengthened the main stem enough to keep it strong. The next summer it was too tall to ever support itself no matter how much I tried to strengthen the main stem. I topped it to keep it from growing taller until it got a stronger stem.
This is actually two trees next to each other. I wound the together hoping that would help. Neither of them are branching out, only growing taller. Ideally I want this to grow tall and then bushy on the top. My home is 62 (F) at night and 68 (F) at day. We have lower humidity in Colorado. It has plenty of light and the window is west facing with south windows as well.
I used Gritty Mix, with Foliage Pro fertilizer and water once a week. In the photo it's leaning against the wall to keep from bending over, otherwise it can't support its weight.