How to make line breaks when typing in the iPhone 6?

If it comes with its own input method, there is only the microphone button to the left of the space. Click it to enable the dictation function, and then say "Newline" to the phone.

The iPhone comes with its own input method. There is definitely a line break. Can you see that when editing a text message, there is a line break option in the lower right corner of the input method. Whether you download the Baidu or Sogou input method, there is a line break, as shown in the picture:

The iPhone's built-in input method has line breaks in the lower right corner: