Modernizing classic WPF application appearance

I have a data integration software that has a windows based client written on on C# WPF framework. There are about 150 .xaml (Window) files that requires modernization on appearance. I am looking for someone who can modernize and beautify the look and feel of these objects. The application should also have option to switch to different themes (colors, fonts etc..)

More details and scope of work will be provided on a zoom meeting.