What setting makes new pages open in current tab rather than new one?
What setting makes new pages (like bookmark clicks) open in current tab rather than new one?
I believe that is the default setting. Some websites do automatically send you to a new tab though.
Regardless you could check the tabs settings on the settings page.
For bookmarks click, the setting is in Bookmark section in Vivaldi settings.
Make sure "Open Bookmarks in New Tab" unchecked.
For links on web page, it's like @Perfect said.
@dLeon Ah, I have no idea why I was looking to set tab behavior in Tabs options. That does solve the bookmark part though.