Use the Organization tab in Microsoft Teams

The Organization tab shows the org chart for your company. When you have a one-on-one conversation with someone, you can see who they report to and who reports to them. You can also search for other people while you're there to see where they appear in the chart.

Another option is to go to the Search box at the top of Teams, type /org, and then the name of the person whose org chart you want to see.