Substitute for Aleppo pepper

These probably won't work if you're looking for a sub because you can't get aleppo pepper where you are, but urfa biber (more chocolate-y) and sumac (more tangy) are also options. You can order all (and more!) online at worldspice.com.

There is also a 'hot paprika' which might also work. If you're making something you can taste as you season, check that it's at a level you enjoy.

Aleppo pepper is just mildly hot. Red pepper flakes (just a sprinkle, as they are hotter than Aleppo pepper), depending on how hot you like things, sweet or hot paprika.