The annotation scale of a viewport allows you to plot annotation at the same height or size regardless of the viewport scale. You can specify an annotation scale for model space and for each viewport in paper space. This means you can use different scales for the viewports in a layout (for example, one for a plan view and one for a detail view), and the annotation will scale and plot at the correct size.
Annotative objects are scaled according to the current annotation scale if they have a corresponding scale representation. If they do not, they are scaled according to the annotation scale in which they were created. Annotative components in other, non-annotative AutoCAD MEP 2022 toolset objects are always scaled according to the current annotation scale.