Apple officially released iOS 13.4 after testing beta on Tuesday March 24, 2020. Update size is approx 860MB but after downloading your iPhone storage will remain the same. It has nine new Memoji stickers including smiley face Heart etc.
You can also share some folder from iCloud Drive just go to iCloud drive long tap a folder which you want to share and options will appear.
Some good changes in Mail section when you are in the conversation view there are some options in below you can move, delete, reply and compose. Another feature if someone sends you an encrypted email and then you reply your reply will be encrypted automatically.
Third party Car play support and Augmented Reality supports audio in USDZ files. There are some upgrades in Apple arcade and fixed many bugs.
Advance support of keyboard and mouse for iPad you can use an external mouse with wire or wireless when you point cursor to any icon it will pop up.