I struggled adding Google Ad-Sense/Bing tracking and indexing. It’s not properly explained on their websites. Yet, WordPress makes it very easy, but unsure if it’s in the right place.
You can add Ad-sense, Bing, Pintrest and Yandex indexing by pasting the HTML Tag code you obtain from these websites.
The path is Tools -> Marketing-> Traffic (Site Verification Services) – it’s on the bottom of the page. All takes a couple of minutes.

Please note that your sitemap is automatically sent to all major search engines for indexing (thank you WordPress), so you may want not to do it. Still, it’s great to have the full control.