SiteSettings is scoped to Controllers, public website document, and templates or views as $this->sitesettings. However, you may need to access it from other objects which do not have it pre-scoped.
The normal way to access SiteSettings would be to fetch its singleton object using SiteSettings::getInstance()
$sitesettings = SiteSettings::getInstance(); echo $sitesettings->getSetting('core' , 'email');
echo SiteSettings::getInstance()->getSetting('contact' , 'tel');
Address: 22a Fishergate York, YO10 4AB · Tel: 01904 636677 · Email: firstname.lastname@example.org