does increasing the amount of baking powder affect the scone in terms of rise?
Up to a point. But if you put to much raising agent in anything then you risk it collapsing and, ironically, becoming more dense, as well as having an unpleasant taste. The structure of the product has to be strong enough and elastic enough to withstand the increase in volume of the gas (and hence, the rise). You shouldn't handle scones too much - this is to stop 'developing the gluten' in the flour which leads to a tough scone. But this also means the structure of it is quite fragile.
tl;dr So yes - you need a raising agent, but too much will lead to a worse result than too little.
Up to a point. But if you put to much raising agent in anything then you risk it collapsing and, ironically, becoming more dense, as well as having an unpleasant taste. The structure of the product has to be strong enough and elastic enough to withstand the increase in volume of the gas (and hence, the rise). You shouldn't handle scones too much - this is to stop 'developing the gluten' in the flour which leads to a tough scone. But this also means the structure of it is quite fragile.
tl;dr So yes - you need a raising agent, but too much will lead to a worse result than too little.
Goodness. You seem like you could write a novel on baking powder and scones.