How to force JS and CSS to be loaded from separate domain in Opencart 2.3?

Question

opencart

I want to load statics from a separate domain.
I figured out the pictures, changed the file:
catalog/model/tool/image.php
here it is:

return $this->config->get('config_ssl') . 'image/' . $new_image;

to this:
return HTTPS_IMAGE . 'image/' . $new_image;
and this:

return $this->config->get('config_url') . 'image/' . $new_image;

to this:
return HTTP_IMAGE . 'image/' . $new_image;
in which file and what to change for JS and CSS I don’t know
Maybe someone implemented it?
There is also in the config, HTTP_CATALOGbut HTTPS_CATALOG
their URL does not affect anything.