Try Shift+Click to select a rectangular cell range, use the context menu for copy/paste, and drag the right cell edge to resize a whole column.

@code { string value = @"

Use the built-in table tools to insert and edit tables.

Feature | Status | Notes
--- | --- | ---
Selection | Ready | Use Shift+Click for ranges.
Copy / Paste | Ready | Works on rectangular cell ranges.
Resize | Ready | Drag the right cell edge to resize the column.

"; }