Hi @kalyan_chakrav1,
Can you confirm if structure node of your root template has responsivegrid configured? If yes and it is not available at template editor, suggest you inspect (using Developer Tools -> Elements section) both in Structure mode and in preview mode and search for the path of responsive grid node in Elements section
Eg: Search for the equivalent path of your project - /conf/wknd-spa-react/settings/wcm/templates/spa-app-template/structure/jcr:content/root (root node has the resourceType as wcm/foundation/components/responsivegrid)