The following instructions may help you to know that how to search Mac App Store for apps to open a specific file extension.
Check also: How to Install Cracked Apps from Mac App Store How to Download and Install an Application from Mac App Store
How to Search Mac App Store for Apps to Open a Specific File Extension
Go to Mac App Store, and in right upper corner you will find Search field, so type there extension:file extension type, for example Extension:jpg
It will sort out and provide all available apps list which may open the files with the extension jpg.