Is it possible to restrict download and print of PDF files in SharePoint online?

HelloSunilK90 

As per my expierence, yes you can restrict the files download on SharePoint Online, by gaving view only permission, which prevent end user from downloading files on Sharepoint. 

View Only permission include view pages, items, and documents. Any document that has a server-side file handler can be viewed in the browser but not downloaded. File types that do not have a server-side file handler (cannot be opened in the browser), such as video files, .pdf files, and .png files, can still be downloaded.  for more Info, please refer to following article https://docs.microsoft.com/en-us/sharepoint/understanding-permission-levels

unfortunately, his Option is available only on the Sharepoint root site, which means you can assign this permission level to the members on the root site, then inherit the permission. 

But as i saw, you want to restrict PDFs only, which can be achieved also using IRM SharePoint Policy.

IRM stand for Information Rights Management, and can use to restrict Office apps ex. prevent files from printing, Outlook ex. to prevent and protect specific emails from being forward for also Exchange Online and Sharepoint. 

Set up Information Rights Management (IRM) in SharePoint admin center:

https://docs.microsoft.com/en-us/microsoft-365/compliance/set-up-irm-in-sp-admin-center?view=o365-worldwide

Apply Information Rights Management (IRM) to a list or library

https://docs.microsoft.com/en-us/microsoft-365/compliance/apply-irm-to-a-list-or-library?view=o365-worldwide

please let me know if i could help you 🙂