Do you mean you want to put your xaml styles in one file and use them in another? yes.
you can do that. You can create a ResourceDictionary to hold your styles and be used by many other files. you just need to include it as a resource in each file or you can add it to the Application.Resources in your app.xaml then it will be available to the entire application.
<Application x:Class="myNameSpace.App"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml">
<Application.Resources>
<ResourceDictionary>
<ResourceDictionary.MergedDictionaries>
<ResourceDictionary Source="pack://application:,,,/SomeDllWithResource;component/Layout/WPFDataGridLayout.xaml" />
<ResourceDictionary Source="myResources.xaml"></ResourceDictionary>
</ResourceDictionary.MergedDictionaries>
</ResourceDictionary>
</Application.Resources>
</Application>
once you've created the Resource dictionary you can include it like above for 'myResources.xaml' that line can be put in the resources section of a specific file or in the app.xaml like the example above.