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The grid visible in the 2D and 3D viewports gives you an indication of how big your objects are. It is recommended to use the grid to check if your objects are the size you intended. Please Scene scale for more details.
The 3D viewport has a grid size indicator at the bottom right of the viewport showing the current grid size. There are two ways to display the grid: Adaptive and Absolute. These options are available in the Preferences (Edit>Preferences>Viewport Rendering).
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- Reset Viewport will reset the viewport to a default perspective view.
- Look at Selection applies to both camera and perspective view and it centers the selection in the viewport without changing the position of the viewer or the camera zoom.
- Center Selection centers the current selection (objects and/ or groups) in the viewport (Shortcut: C).
- Center Scene centers the entire scene in the viewport (Shortcut: Shift + C).