Epic Games does not have a standalone mobile app for their game launcher, similar to their desktop version. However, they do offer several of their games as mobile applications, the most notable of which is Fortnite.
Fortnite is available for download on both iOS and Android devices, Fortnite is not available on the Apple App Store due to ongoing litigation between Epic Games and Apple. Android users can download Fortnite directly from the Epic Games website or through the Samsung Galaxy Store on Samsung devices.
For updates on Epic Games' mobile application status or changes, I would recommend monitoring the official Epic Games website or their official social media channels.
If you're referring to a different app from Epic Games, or if there have been developments after my last training data, please provide additional details or consult the most recent sources.