Labels are scaled relative to the drawing scale in model space, and are scaled to the assigned text height in paper space, regardless of the viewport scale.
In model space, label text height is controlled by the drawing scale and the text height as specified in the label style.
For example:
In paper space, label text always appears at the same height regardless of the paper space viewport scale.
For example, label text height set to 0.1 appears as 0.1 inch on the plotted sheet, regardless of viewport scale or zoom level.
You must use the REGENALL command to update the label display on the screen when you either change the paper space viewport scale or zoom.
Labels in drawings that you xref also respect the scale of paper space viewports, so you can create project documentation in paper space at the correct scale for several drawings at the same time.
When working with labels in a viewport, do not use the Annotation Scale at the bottom of the drawing window as this will change the viewport scale.
When working with labels in a viewport, you should use one of the following methods: