As trees are usually much taller than us, it is common is for us to look upward at leaves or minimally view them from a side perspective. Also typical is for the leaves to be facing, at least to some degree, upward and for the light to be reaching the leaves most strongly from above. While photographing glowing backlit leaves from underneath is commonly recommended (and a good tactic), the top of leaves generally have the strongest color with that color facing the light. Thus, capturing the best leaf color in the best light often means photographing the top of leaves.
Because most leaves (on trees at least) are higher than us, moving in close to the tree can diminish the amount of color seen. Moving farther away, unless that distance means a lower elevation, can provide a more colorful view of a tree by simply lowering the angle of view. Better is to get a higher vantage point. This means going up on a hill, up on a deck, up in a building (shooting from an open window for example), up on a ladder, etc.
A photo accessory that I've long considered acquiring, one that would help greatly in this regard, is a Bucket Truck. I know, you think I'm kidding, right? Not so. I think having such a truck would be a competitive advantage and I am always seeing locations where I could make use of one.
I don't know if that idea will ever come to fruition for me, but more popular is the use of drones. While the rules and regulations book for use of these devices is still being written, drones can get to many locations that would previously have required a bucket truck, crane or helicopter. Getting above the leaves is no problem for a drone.
If moving up means moving back, a longer focal length lens may be desired to keep the same framing and that the perspective will change should not be overlooked.
I was evaluating the Tamron 35mm f/1.8 Di VC USD Lens and while looking down the steep hill from our house, a beech tree with various shades of yellow and salmon-colored leaves caught my eye. At 35mm, the tree was tiny in the frame, so I went down to it. The closer I got, the less I was noticing the color patterns that initially caught my attention and the more I was looking across the side of the leaves, leaving the bare woods showing through the color. While still beautiful, this was not the image I had envisioned from the top of the hill.
I took some photos that I liked at 35mm, but then went back to the house to mount the Canon EF 100-400mm f/4.5-5.6L IS II USM Lens. With the narrower angle of view, I could easily fill the frame with color and the downward view on the leaves left few holes into the background.
The next time you are looking at beautiful fall foliage, consider moving to a position that affords a downward view to maximize the color available to you.