There are no filters for that, but you can preselect filters with url parameters:
– Select your filter(s) in the ui,and copy the url
– use the url on a link, or a form action
Okay, actually my requirement was for a clean url, with filter selected..
I found this code, but didnt see any hook to use it
[class-wpsolr-option.php]
public function get_facets_items_is_default() {
return $this->get_option_value( true, __FUNCTION__, self::OPTION_FACET, self::OPTION_FACET_FACETS_ITEMS_IS_DEFAULT, [] );
}