Substitutes for Sweet Paprika:
If it's just a small amount, like half a teaspoon or less, you could conceivably get away with substituting chili powder, which is mainly paprika along with other seasonings such as garlic, salt, cumin, and a bit of cayenne. It's slightly hotter than plain paprika, but not overwhelmingly so. Some other ground red peppers like ancho chili powder, chipotle powder, or hot sauce would also work. Chili powder will also suffice if the paprika is just being used for a garnish. With these spices, you can go with a 1:1 ratio of the substitute spice to the paprika amount needed.
Cayenne Pepper Vs. Chili Powder
RED PEPPER FLAKES
Bell peppers definitely have a less spicy flavor and heat level than the peppers used to make hot paprika. But I have tried bell pepper powder in many of my recipes, and it worked just fine.
Most countries have their own variety of chili peppers, ranging from poblano, serrano, Tabasco, jalapeno, peri-peri, habanero, cayenne and numerous others. Originating in Mexico, the red chili made its way across the world and is used in many cuisines. Many varieties may also be used fresh and green or red or pickled instead of dried and powdered.