You can make soup less spicy by adding a bit of milk, broth, or water or nut butter to help dilute the spiciness in the soup.
When you have food that is too spicy the best way to fix the food that is too spicy is to dilute the food.
For example if you have soup that is too spicy you can add additional water, broth, tomatoes, etc to the soup and that will make the soup less spicy.
You can also serve the spicy food with bland starchy food or add some nut butter.
Also drink some milk with the spicy food if you cannot get the spicy food toned down enough.
But the only real way to get the food to become less spicy is too dilute the spiciness if possible.
When I make soup and it turns out too spicy for me i add some chicken broth or beef broth to the soup and it helps to get rid of the spiciness.