Probably not. Although I don't actually own a 156 I do own a few 3" barclay figures. They are huge even by standard gauge sizes.
Grandpa built quite a few structures for his standard gauge Xmas layouts in the late 20's. None of the trains survived the depression but I inherited the surviving structures and about 60 figures that he used on his layout. These were the 2 1/8" Britains farm and railroad figures with a smattering of John Hill and other manufacturers of that scale (54 mm). The lead figures best suited to O gauge are the 1 5/8" Barclay 'little people' sold in the late 50's. Lionels own figures are 1 1/2".
A platform is a fairly simple construction project. Start with a 1x3 or wider. Add three center posts and a couple of Orange crate slats for a roof. Paint for effect. Add a slot down the middle of the platform and print advertisement bulletin boards on light cardboard at the correct scale to occupy the slots.
Grandpa would approve!