Change Tabs preferences in Safari on Mac
In the Safari app on your Mac, use Tabs preferences to choose how pages, links, and tabs work in Safari windows. To change these preferences, choose Safari > Preferences, then click Tabs.
Open pages in tabs instead of windows
Choose one of the following:
⌘-click opens a link in a new tab
Change what the listed shortcuts for opening links do.
When a new tab or window opens, make it active
New tabs or windows open in front of the one you’re currently viewing.
Use ⌘-1 through ⌘-9 to switch tabs
Use keyboard shortcuts to select one of the first nine tabs in the tab bar.