The text size will be taken from the current text style. That is, you need to configure the default text height before calling the command. This is done using the system variable TextSize or in the dialog box for setting the current text style _TextStyle. Moreover, the height that will be printed on paper must be set, and not the height in the model. The program itself will recalculate this height in accordance with the scale of the viewport and assign it to all texts.
Switch to the layout having a viewport.
Call the TextHeightUpdate command
If there is only one viewport, then the command uses it, without unnecessary requests. If there are several viewports and none is selected, the command will ask you to select a viewport.
Then the command will find all the MultiText visible through this viewport.
When you use this command on all sheets, then all the texts on the printouts will look the same. But in the model, they will probably have different heights.
If one text is visible in several sheets through viewports with different scales, then the TextHeightUpdate command will not help you, you should make the text annotative.

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