In Revit, line weights are pulled from the project settings > line weights. This holds true for linked files, which will also utilize their specific line weight settings.
Let’s look at the following common scenario and example line weight:
-You have a host architectural file, where walls object style cut weight is set to 5.-You have a linked structural file, where walls object style cut weight is set to 7.
-You want the weights to appear the same thickness in a section view, so in the host project you set the Visibility/Graphic Overrides > Revit Links > link Display Setting to By Host View.
-This replaces the object style cut weight for walls in the linked file to the host file setting. So in this example, instead of using 7 for the linked walls they will now utilize the host project cut weight of 5....