You can try editing the pref_default_overrides in the installation directory to see if it will override some preferences. After enabling an option and closing Opera, you'd have to look in the "Preferences" file in the Opera profile folder though to see what node(s) the preference is under and what name and type of node it is and what type its value is. JSONedit will help with that.

If that works, you'd have to figure out how to edit the override file with a batch file. It's JSON, so...

If that doesn't work, you'd have to add/modify the settings to each Opera profile.

Besides that, I don't know. Opera doesn't support policies from the registry like Chrome and Vivaldi do.

As for extensions, I'm not sure what you can do there besides placing unpacked versions in the "extensions" folder in each Oepra profile folder. You'd install the extensions in Chrome, close Chrome, and use the unpacked folders from the extensions folder in the Chrome profile. But, even if this works, they extensions would problem be off by default or the user would have to click "install" for each on the opera://extensions page. I don't think you'll get that far though as installed extensions have to be approved by the user and are protected by Opera with keys. You'd have to go through some hoops to get it to work. You might have more luck with standalone installations of Opera though as they're a little lax when it comes to extension protection.

Hi,

AceStream auto installs it's Extension when a "New" Browser is launched.
It locates the CRX locally.
Then the Browser updates to the newer version.

You may check it to find out how is made all that magic xD

For some Settings, check out the Help to find out what and where are the important files.

Some of them can be used on other users/computers, try modifying a Profile and Copy/Paste the settings.
It would need to be applied after first Opera restart.

--
"Off Topic Tip"
Follow the Signature's Backup | Reset link.
Take the opportunity to start a Backup plan and even create a Template Profile.

Windows 7 (x64)
Opera Back up | Reset

What I need is the ability to configure Opera from a batch file, either before, during or immediately after installation, to set the following, among others:
Set "show bookmark bar" ON
Set "block ads" ON
Set Block trackers" ON
Set VPN ON
Set "Ask where to save each download" ON

In addition, I want to preinstall some add-ons, including:
"I don't care about cookies"
"Google translate"

These all need to be set when Opera is installed, before it is launched for the first time, so they will be the default settings and add-ons for every new user.