https://wccftech.com/download-ios-13-1-beta-released-for-iphone-ipad-ipod-touch/

In a rather surprising move, devs can now download iOS 13.1 beta for iPhone, iPad and iPod touch from Apple.

Quick update: You can download iOS 13.1 beta without a developer account. For more details, go here: Download iOS 13.1 Beta Without Developer Account on iPhone, iPad