Designing related query

You can try adding cu-categories to the class list of the Category List Block.

Adding Custom Classes: https://wordpress.com/support/wordpress-editor/adding-additional-css-classes-to-blocks/

Then add this CSS through Appearance > Customize > Additional CSS:

ul.wp-block-categories-list.cu-categories.wp-block-categories {
    display: flex
}

ul.wp-block-categories-list.cu-categories.wp-block-categories > li {
    list-style: none;
    padding: 4px 6px;
    background-color: #dddddd;
    border-radius: 6px;
}

ul.wp-block-categories-list.cu-categories.wp-block-categories > li:not(:last-of-type) {
    margin-right: 16px;
}

ul.wp-block-categories-list.cu-categories.wp-block-categories > li >a {
    text-decoration: none;
}