After a bunch of reading and testing, here’s the theme.json file I came up with. It adds all the layout, sizing, spacing features of Gutenberg blocks, but keeps them neutral so to speak, no pre-sets, so they’re available for use. This is all that’s needed; this theme.json file goes in the theme’s folder…
{
“$schema”: “https://schemas.wp.org/trunk/theme.json”,
“version”: 2,
“settings”: {
“appearanceTools”: true,
“color”: { },
“layout”: { },
“spacing”: {
“blockGap”: true,
“units”: [“%”, “px”, “em”, “rem”, “vh”, “vw”]
},
“typography”: { },
“useRootPaddingAwareAlignments”: true
}
}
Caveat: I’m not a theme developer, so this theme.json file seems to be working for our current website in need, but your mileage may vary.