You can use an active or capacitive pen to apply style while typing:
Underline to title or make bold, and draw a square to highlight. If you want to insert handwritten text into a typed text just use an upward pen gesture to create a space, then begin writing with your active pen. Of course, you can insert typed text into handwritten text too. Simply make an upward gesture with the pen to create a space, tap the keyboard icon in the navigation bar to open the keyboard, then tap the space with your finger to place the cursor. You can now begin typing.