go down to the next line in mobile app

when pressing the "enter key" while writing a message in the mobile application, the cursor should go down to the next line.
instead at the moment it sends the message, this is unexpected behavior since the enter key serves as "go to next line" in every possible messages app. so basically at the moment its impossible to go to the next line. more over there is a dedicated button for sending out the msg, why to config the same functionality for the enter key?