Yes, it's possible.
First create a folder of bookmarks containing the pages you want to have appear as tabs when you start Safari.
Once you've got that bookmarks folder set up, go into your General Safari preferences. At "New windows open with:" select "Choose tabs folder ..." as per the following screenshot:
.... and select the bookmarks folder you set up before.
Quit and restart Safari. Do the contents of the bookmarks folder open in tabs in a new window?
(To change what tabs you have opening in a new window, just change the content of the bookmarks folder you've selected in your preferences.)