Home tab > Properties group > 
(Linetype) menu > Scale linetypes, SCALELTYPE
Scale linetype definitions in the active drawing. All objects containing the linetype will be scale according to a user-defined scale factor.
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Select linetype from the list, or click Pick and select the linetype from an object.
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Enter the scale factor and click OK.
If the linetype definition is reloaded from a linetype file, the scaled linetype definition will be replaced.