For a truly cinematic look for your drone video footage the shutter speed must be reduced to 1/50 second for 25 fps video. While cameras can use the aperture to reduce the light hitting the sensor and thus reducing the shutter speed, drone and smartphone do not have aperture control.
One easy way to do that is to add a neutral density or ND filter to achieve the desired shutter speed. Join DM Productions describing how ND filters are to be used.