In Messages, to create a new message tap the pencil-in-a-square icon in the upper right corner.
In Notes, to create a new Note, tap the pencil-in-a-square icon in the lower right corner.
In Calendar, to create a new appointment, tap the + icon in the upper right corner.
In Reminders, to create a new reminder, tap the + in a blue circle in the lower left corner. At least it offers a text label "New Reminder"
These are all Apple apps and they all do it differently. And that's not even getting into gestures and other actions that you just have to stumble upon to even know they exist.