You can override any xref layer property on referenced layers. Depending on how you want to control the display of the xref layer properties—always synchronize and reload the xref layer settings or selectively choose a few layer properties to always synchronize and reload the current xref layer settings and keep the overrides you have applied to the other xref layer properties. Use XREFOVERRIDE, VISRETAIN, and VISRETAINMODE in combination to get the appropriate behavior with your xref layer property overrides.
The VISRETAINMODE system variable provides you with more options on how you want to control and manage the xref layer property overrides in your current (host) drawing when you have set VISRETAIN to 1. By default, the VISRETAINMODE, a bitcoded system variable, is set to 0. To specify more than one layer properties that you want to automatically sync, enter the sum of their values. You can choose any combination for the xref layer properties that you want to reload from the referenced layer settings even when you have set VISRETAIN to 1. But, if you do not want to synchronize xref layer properties, you should keep the default value for VISRETAINMODE.
If you have a legacy drawing, which you opened in AutoCAD 2018.1 or later versions, any changes to the referenced layer property will not get updated automatically in the current drawing regardless of what value you have set for your VISRETAINMODE sysvar (changed the default value). This behavior ensures that anytime you open a drawing that is authored in an earlier version of AutoCAD 2018.1, it maintains the visual fidelity between AutoCAD 2018.1 and previous AutoCAD releases and there is no change in behavior.
To make VISRETAINMODE take effect for legacy drawings, you need to save the current drawing in AutoCAD 2018.1 and reload the xref drawing to see the changes.