The lightning arrow spell says:
The next time you make a ranged weapon attack during the spell’s duration, the weapon’s ammunition, or the weapon itself if it’s a thrown weapon, transforms into a bolt of lightning. Make the attack roll as normal. The target takes 4d8 lightning damage on a hit, or half as much damage on a miss, instead of the weapon’s normal damage.
When I hit with lightning arrow, do I add my Dex modifier and or Sharpshooter's extra damage to the damage of the spell?
Example: 4d8 + 5 + 10