How do you apply bold or fontWeight to a text range using the API?

The following works for underline:

textNode.setRangeTextDecoration(index, index + length, ‘UNDERLINE’);

But the following does not appear to work for bold:

textNode.setRangeTextStyleIdAsync(index, index + length, ‘bold’);

What is the correct way to use the API to format a range of characters within a text node please?