How to modify theme.json child theme

Hi,

I have created a child theme of 2023 (with the plugin Create Block Theme), and I want to add changes to the theme.json. Can you tell me how can I do that?

I know, I have to go to /wp-content/themes/twentytwentythreechild and edit the theme.json file, but I don’t know how to declare things properly.

For exemple, if I need to change “fontSizes” property, to modify the sizes of large, x-large…, how can I do that inside the theme.json child theme?

Thank you!