How to print day and week in scheduler?

The Scheduler can print (or export as image) the current view or a section of it using the exportAs() method.

For more details and an example, please see the documentation:
https://doc.daypilot.org/scheduler/printing/

See also:
https://api.daypilot.org/daypilot-scheduler-exportas/

How to print for particular day ?

The following tutorial explains how to export a selected date range in the Scheduler component:

https://code.daypilot.org/73551/html5-scheduler-pdf-export-javascript

It uses area: "range" option to limit the exported dates. You can use similar config it to export a single day:

dp.exportAs("jpeg", {
  area: "range",
  dateFrom: "2022-01-01",
  dateTo: "2022-01-02",
}).print();