I found xpath
I'm trying to set new ID and there is an error:
magento config:set design/theme/theme_id 7 The "design/theme/theme_id" path does not exist
What's wrong with it? Is there described reason why it doesn't work?
Other configuration paths work fine.
In this case related question-answer doesn't work: How to configure Mangento 2 Theme/Design via the Command-Line? (It doesn't work neither by using