If I have 1 Django project and multiple Django apps. Every Django app has it's own requirements.txt and settings. Hence every app has its own docker image. My doubt is, can I execute code from one Django app to other Django app while both apps have a different container?
No, in the context of Django an “app” is a code level abstraction so they all run in one process, which means one image. You can, sometimes, break each app into its own project and have then communicate via the network rather than locally, this is commonly called “microservices” and smaller images is indeed one of the benefits.