Once Again: How to Remove Option from Gutenberg Editor for Specific Block in theme.json

Since WP 5.8 we can define various settings in the theme.json which is much appreciated and really helpful. But there are still some options I cannot find, e.g. how can I remove the layout panel from the core/group block?

In theme.json, I tried (not sure about the layout-key):

{
    // ...
    "settings": {
        // ...
        "blocks": {
            "core/group": {
                "layout": false // or [] or {} <-- no effect
            }
        }
    }
}

or

{
    // ...
    "settings": {
        // ...
        "blocks": {
            "core/group": {
                "layout": {
                    "customLayout": false // <-- no effect
                }
            }
        }
    }
}

The following answers here were quite close:

• How to remove specific panels in the editor (Gutenberg) when editing a block (via right panel)?
• How to remove unwanted panels inside InspectorControls from core blocks in Gutenberg
• Remove border radius setting from the Gutenberg button block?

So my question is

Where can I find a complete list of all the possible settings for core-blocks in theme.json?

Alas, the official twentytwentyone theme does not contain a such file.