Apple released the fourth public beta of iOS and iPadOS 13. The first public release came on June 24th. The beta does come with bugs just like the developer betas and so users are advised to proceed with caution.
iOS 13 brings lots of changes including but not limited to a Find My a combined Find my iPhone and Find my Friends, Dark Mode, Memoji characters for iMessage for older devices, Voice control and much much more which you can read about here.
For registered testers you can download the profile from here then go to the Settings app –> General –> Software Update and following the onscreen instructions.