"Winged humanoid" style anthros would not be able to fly horizontally. Why? Because if you have wings sticking "out the back" and not the sides, how are they going to get a full flap out of them? A half flap yields much less power than a full one, and that's without getting into all the science about wing size/lift vs. body mass.
This is why angels are considered to be bugs. Animals - wings instead of hands. Bugs - wings on the back, as additional pair of limbs.
If they're being compared to real birds, then they can probably achieve flight if they have hollow bones. You know, like actual birds.
No. Because with the size also comes mass, and to support it you need additional muscle mass. After reaching certain mass flying simply becomes impossible, because amount of musclemass needed to lift you from the ground becomes higher than mass that your wings are able to hold. Matemathician or physicist (and a native speaker) would be able to explain it better. Dunno. Ask Fallowfox.
It's exactly the same as with bugs - their skeletal and muscular system becomes inefficient after reaching certain mass so it's impossible for them to be bigger than X in earth gravity (not to mention limited breathing and oxygen delivery systems efficiency). Same applies to mammals. To every living thing.
It can be pictured by a simple chart.
(of course it's more complicated as in this case I'd also need to take into consideration wing surface size and shitton of other factors, but two mentioned are the most important)
By perfect I mean something that makes sence and can exist de facto
By imperfect I mean something that makes no sence and can exist only theoretically (or exist de facto for a short period of time as a blind alley of the evolution, or in favourable conditions, or after losing it's primary function - like wings of the flightless birds)
By impossible I mean impossible in current conditions, even in theory.
Of course that chart varies, depending on the movement mechanism (so, type of muscles, internal/external skeleton, skeleton and muscle material et cetera), oxygen levels, gravity, air density, air pressure, et cetera.
That applies to everything, vechicles and airplanes included.