Apple has just released iOS 14.0.1 for iPhone. You can download the update on your iPhone now by heading to Settings > General > Software Update.
Here are the complete release notes for the update:
This update includes bug fixes for your iPhone.
Fixes an issue that could cause default browser and mail settings to reset after restarting your iPhone
Addresses an issue that could prevent camera previews from displaying on iPhone 7 and iPhone 7 Plus
Fixes an issue that could prevent your iPhone from connecting to Wi-Fi networks
Resolves an issue that could prevent sending email with some mail providers
Addresses an issue that could prevent images from appearing in the News widget