I am surprised no one came up with a working solution in the last 9 years.

You can simply add & # 1 0 ; (without spaces) to your placeholder text, browser will register it as line feed.

Is it possible ?? ;) Have you tried \n \r ?

Only by formatting with multiple spaces, e.g.:

1st line of placeholder starts here                                         2nd starts here            etc    

If the size of textarea is fixed, browsers will show such long texts as if they were on multiple lines.

You'll have to fine-tune the number of spaces to make placeholder text look as you like.