Draw the destination bounding box via the AutoCAD box command.
Select the Flexblock icon in the AutoCAD ribbon to start the dialog box. Use the Orientation Line button to draw an orientation line along one bottom edge of the bounding box.
Select source block drawing and click OK
Select both the orientation line and bounding box, and press <Enter> to fill objects into the bounding box.

3DSTRETCH
In Model Space, select Top view in WCS.
Select 3DSTRETCH icon in AutoCAD ribbon and draw a selection window over objects to stretch (same as in the 2D AutoCAD stretch command)
Select a point in the model space and click another point in the direction and distance you want to stretch the 3D object. (use Polar Tracking for accurate directions.) 

The installer that ran when you downloaded this app/plugin from the Autodesk App Store will start installing the app/plugin. Or, simply double-click the downloaded installer to install the app/plugin. You may need to restart the Autodesk product to activate the app/plugin. To uninstall this plugin, exit the Autodesk product if you are currently running it, simply rerun the installer, and select the "Uninstall" button. Or, click Control Panel > Programs > Programs and Features (Windows 10/11) and uninstall as you would any other application from your system.

Compatible with AutoCAD 2012 and later versions.
Works with Windows 10/11 (64-bit).

In rare cases, AutoCAD may need to be restarted after the first installation to fully load the plugin.
The user has to manage the minimum size of the destination bounding box for each source object. Objects don't always stretch correctly if the destination size is too small.