Apply calendar/work template to project level (in Project for the web)
There is only way to set calendar/work template to Resources. But calendar/work template does not apply to project level.
Thanks for the suggestion. Project for the web does support project level calendars in addition to resource level calendars. This article has more information to get you going https://docs.microsoft.com/en-us/project-for-the-web/create-and-apply-a-work-calendar
Having different Calendar types with flexible working/Non-Working times in Project and Task level is very crucial even for IT Projects.
Resource Calendar also would be required if other types of the resource (material, generic, ...) were available to allocate.