Activate a Perspective or orthographic viewport. > Viewport Navigation controls > Zoom Extents flyout

The Zoom Extents flyout displays the Zoom Extents button and the Zoom Extents Selected button.
Zoom Extents centers all visible objects in an active Perspective or orthographic viewport. This control is useful when you want to see
every object in a scene in a single viewport.
Zoom Extents Selected centers a selected object, or set of objects, in an active Perspective and orthographic viewport. This control is useful
when you want to navigate to small objects lost in a complex scene.
Zoom Extents—Centers and magnifies views so all the visible objects in the scene are shown in a single viewport.
Objects can be excluded from zoom extents all if the Ignore Extents box is turned on under Object Properties.
Zoom Extents Selected—Centers and magnifies views so just the selected objects or sub-object selections in the scene are shown in a single viewport.
If no objects are selected, the effect is the same as Zoom Extents.