Extend PHP regex to cover “srcset” and “style” attributes

I was able to use the following regex to cover all tags & attributes with protocols:

/<(?:input\b[^<]*\bvalue=[\"\']https?:\/\/|link\b[^<]*?\brel=[\'\"]canonical[\'\"][^<]*?>)(*SKIP)(*F)|https?:\/\//

This is the updated section:

# If 'Relative' option is selected, remove domain from all internal links
$exceptions="<(?:input\b[^<]*\bvalue=[\"\"]https?:\/\/|link\b[^<]*?\brel=[\'\"]canonical[\'\"][^<]*?>)(*SKIP)(*F)';
if ( $this->option == 2 ) {
    $website = preg_replace( '/https?:\/\//', '', home_url() );
    $links = preg_replace( "https://wordpress.stackexchange.com/" . $exceptions . '|https?:\/\/' . $website . "https://wordpress.stackexchange.com/", '', $links );
}
# For all external links, remove protocols
$links = preg_replace( '/<(?:input\b[^<]*\bvalue=[\"\']https?:\/\/|link\b[^<]*?\brel=[\'\"]canonical[\'\"][^<]*?>)(*SKIP)(*F)|https?:\/\//', '//', $links );