You can use the custom CSS and JS loader to set default css styles for vs code when ever it is opened.
just add the styles
https://i.sstatic.net/EDRsLHRZ.png
https://i.sstatic.net/2f6tO4nM.png
its best to take a look at Glenn Raya's video, he showed and explained how to customize vs code with custom css styles and js scripts.
https://www.youtube.com/watch?v=9_I0bySQoCs&ab_channel=GlennRaya