How to set max line length in Android Studio code editor?

If you need not a soft wrap,
but actually, brake one long line onto several lines you need:

Go to Preferences(mac) or Settings(windows) -> Editor -> Code style -> Java/Kotlin -> Wrapping and braces (tab) -> Check “Ensure that right margin is not exceeded”

Now try to reformat your code:
press
OPTION (ALT) + CMD + L on your Mac
(or CTRL + ALT + L on PC)

Edit 13.02.19

As noted in comments this option seems not available in settings for Kotlin.
However, there is a workaround to manually add it.
Here is what it takes to make it work:

1. Export the settings scheme.
   

2. Open saved xml file.

3. Find <codeStyleSettings language="kotlin"> tag (or create)

4. Add the WRAP_LONG_LINES setting manually:

   <codeStyleSettings language="kotlin">
      ...
      <option name="WRAP_LONG_LINES" value="true" />
   </codeStyleSettings>
   

5. Save edits and and import back the scheme.

6. Here you go!