No. There is no canon explanation why helmeted soldiers with limited vision would be able to make use of a scope on a rifle they mostly hip fire anyway. There is one example of a stormtrooper raising their rifle to fire, but in this example it cannot be made out whether the stormtrooper is using their scope or merely raising their rifle to brace for recoil (maybe this explains why they are usually so inaccurate when firing from their hip?).
An out of universe answer would be the reason they added the scopes to the E-11 Blaster Rifle was to make it better replicate existing earth weapons, even though the Blaster rifles in the star wars universe are rarely used for long distance pitched assaults, but more frequently for corridor shootouts.
The analysis I have made upon the aforementioned scene where a stormtrooper appears to raise their weapon is as follows:
- You can clearly see from the diagram below the orientation of the gun and the stormtroopers visor do not line up
- The stormtroopers helmet eye-holes do not line up to the scope
A better explained theory as to what the stormtrooper is doing is as follows:
- The stormtrooper, seeing Han has raised his weapon in order to improve accuracy by reducing the recoil on his blaster.