If you want quick action to appear on Page layout, all you have to do is add it in Salesforce Mobile and Lightning Experience Actions as shown in below image
Unfortunately this did not worked for Case & Work Order Page layout in Lightning experience.
I almost spent around an hour and found below gold statements in Salesforce documentation
Actions on user profiles, cases, and work orders can appear in a different way than on other records.
Actions on the user profile page come from the Quick Actions in the Salesforce Classic Publisher section of the global publisher layout. Only standard Chatter actions appear on the user profile page, regardless of which actions are assigned to the User Page Layout or the global publisher layout.
When feed tracking is enabled for cases or work orders, the page-level action menu on those records contains only custom buttons and supported standard buttons. Quick actions appear on the Chatter tab.
So, quick action would not appear at top of page layout or Highlight Panel if feed tracking is enabled. In my case, for time being I disabled feed tracking on case and it worked.
Hope this blog post will save an hour of someone 😉