A simple installation can be done as

Opera_57.0.3098.116_Setup.exe /install /silent /desktopshortcut 0

Whole set of parameter can be found by running the following command.

Opera_57.0.3098.116_Setup.exe /?

Output is fairly long

===================================================================

Opera Installer 57.0.3098.116 Stable

The following command line parameters affect the behavior of the installer:
  silent
    Run the installer fully unattended. No dialog will be displayed in this mode. If it isn't running with sufficient privileges, the installer will fail instead of prompting the user.
  runimmediately
    Run the installer mostly unattended. The installation will start immediately and the progress dialog will be displayed. The installer will prompt the user for elevation if needed.
  language=LANGUAGE
    Install Opera in the specified language.This language will also be used during installation.
    Default value: The Operating system UI language.
  installfolder=FOLDER
    Install Opera in the specified folder.
  allusers=[0|1]
    If true, install Opera for all users on the system.
    Default value: True when running from an administrative acount.
  copyonly=[0|1]
    If true, the installer will only copy the files to the installation folder and will otherwise not perform any modification on the system.
    Default value: False.
  singleprofile=[0|1]
    If true, the installer will set up Opera to use a singleprofile located in the installation folder.
    Default value: False.
  setdefaultbrowser=[0|1]
    If true, make Opera the default browser for this user or computer.
    Default value: True for Opera Stable.
  desktopshortcut=[0|1]
    If true, create a shortcut for Opera on the desktop.
    Default value: True.
  startmenushortcut=[0|1]
    If true, create a shortcut for Opera on the start menu.
    Default value: True.
  quicklaunchshortcut=[0|1]
    If true, create a shortcut for Opera on the quick launch menu.
    Default value: False on Window 7 and later. True otherwise
  pintotaskbar=[0|1]
    If true, pin Opera to the taskbar.
    Default value: True on Window 7 and later. False otherwise.
  import-browser-data=[0|1]
    If true, Opera is set up to import user data from the previously default browser when creating new user profiles.
    Default value: True.
  enable-stats=[0|1]
    If true, Opera will by default gather and report statistics.
    Default value: True.
  enable-installer-stats=[0|1]
    If true, installer will by default gather and report statistics.
    Default value: True.
  launchbrowser=[0|1]
    If true, Opera is launched once the installation is completed.
    Default value: True.

Languages available for the language option:
be, bg, bn, ca, cs, da, de, el, en-GB, en, es-419, es, fi, fil, fr-CA, fr, hi, hr, hu, id, it, ja, ko, lt, lv, ms, nb, nl, pl, pt-BR, pt-PT, ro, ru, sk, sr, sv, sw, ta, te, th, tr, uk, vi, zh-CN, zh-TW

Features available through command-line switches:
        --with-feature:installer-experiment-test [Enabled by default: false]
        --with-feature:installer-use-minimal-package [Enabled by default: false]