Dynamic Styles
There are several common ways to achieve this.
Option 1: Style Overrides
You can use the style override fields in the Text layer to set a font color or size by just adding something like {{ row.titleColor }} into the appropriate field.
Option 2: dynamic default styles
For this one you specify the name of the style in your row data and then put it into the "Default Styles" field under Text Formatting in your Text layer.
You can even combine this with other static styles in a comma separated list due to style inheritance.
Option 3: dynamic style tags
For this one you specify the name of the style in your row data and then just invoke the tag using that, like this:
<{{row.style}}>your text here</{{row.style}}>
Option 4: style tag overrides
If you have a color you wish to apply to some text, you could use a style tag override like this in the Text field of the Text layer:
<body fill="{{row.color}}">{{row.description}}</body>
Option 5: Encode styles in the text in your dataset
If there is a style you wish to apply to a text element, you can actually do that right in your dataset like this:
This is <blue>cool</blue>.
You can learn more about style tag overrides on the style tags page.