The only real size of a dick is when it's measured in its erect state.
Small-framed men can look to have a longer dick if they have any hang at all in a softer state (there are multiple states of flaccidity). It's often just an illusion. A good example is Evan Stone. When he's softer, his dick has about a 4-5 inch floppiness to it (not all dudes get good "floppiness" at certain times; they're either all shriveled up, going towards a semi, or rock hard). But his peter is not as long as you think as he's not a very big man. I've seen him in scenes where his dick was not that floppy before, too (due to temperature, other factors, etc.). When he's fully erect, though, nothing impressive in the least (maybe 6 inches?). He also lacks girth. Not hard to dick him down. That said, Evan can still trick your eyes when he's in a softer state.
A bodybuilder once said when his thighs got real big, his nice hang went away. In other words, he dick looked smaller in its flaccid state because his legs got so bulked up.
The biggest dick I know of is on a big-framed man: Shane Diesel. And many of the black male porn stars are very big-framed with big-ass dicks.
Dick size is just not length, but also girth. You combine the two for overall penile volume.
Yes, a big-framed man can have a very small dick, but you have to take his build into consideration. And also, you haven't seen his boner, so...
Don't get me wrong: there are small-framed dudes who have big dicks, but you have to consider the cock independent of the smaller-framed body.
A small-frame dude with a true big dick? Yes, Matt Hughes. But remember, if Matt were a big man with big thighs, etc., his dick would still appear as big in penetration shots, and in sit-down jack-offs. But in the locker room, it wouldn't appear to have as low of a hang. Get my point?