Hmm... I don't think there is, yet. I've been wanting to add some additional line height tools, so I think this will be possible for me to add. I'll try to add it soon!

Alright, added it! Submitted v1.8.16 to the asset store, and it's already live on itch.

I added a <y=float> tag that can be used to set the y offset of text, and in addition to this I added ^{and _{for superscript and subscript. What these tags do is essentially the same as typing <s=0.5><y=0.5>, except it uses values that you can set withing the TextData Inspector, under "Master".} or} will also cancel size tags, so another should be typed afterwards. if you were already using one, STM has HTML-like tags, but they don't "stack" in the same way as HTML tags...

Can't believe I forgot to add this, thanks for pointing it out!