For the sake of experiment, I decided to create a personal theme. It is written that the settings are changed via "Noesis.settings", but there is no result.

We are going to need more details to investigate the problem. Your theme is not applied when you enter Play mode? Does it work if restarting Unity?

Did not accurately describe the problem. The theme was changed in Unity, but it was not updated in Blend. Solved the problem by replacing the link to the ResourceDictionary in App.xaml

Thanks for the feedback! Marking as solved