You can target Custom CSS to specific Named Styles using the approach James mentioned above.
He has a style named sthm-icon which is applied to the tile and he targets it in Custom CSS with the format .--theme-style-{{style-name}} so in this case it’s .--theme-style-sthm-icon
Since it’s just normal CSS under the hood you can use any of the CSS selectors that are available in Custom CSS. You could target specific Tile Types since they are included in the classes applied to each tile and really any other attribute in the DOM. Each tile technically has it’s own ID that is persisted, so you could even target a specific tile (without a Named Style) applied if you wanted.