Command: TEXTFIT
Select Text to stretch or shrink: Use an object selection method
Specify end point or [Start point]: Specify a new end point, or enter S to specify a new start point
Pick new starting point: Specify a new start point
ending point: Specify a new endpoint

Usage Example:
Fit labels within enclosed borders by setting a new text width.

Select text:

Select a new endpoint:

Text size shrinks: