Auto-resizing text boxes as part of a style?

I have an extremely complex document with at least 10,000 text frames. I don't want to use auto-size for everything, but there are certain types of text frames (about 2500 or so, if not more) that would desperately benefit from the ability to dynamically resize (adding characters to the right). The document was created over 20 years ago in Quark and is continually updated, so this is not a one-off thing. I'd like to be able to say "any frame containing paragraph style XXX, apply auto-resize to it.

If that's not feasible, it there a way to automate the conversion of a fixed-size text frame to an auto-sized frame? Select the frame, apply a keyboard shortcut and instead of getting an overflow arrow, it just resizes the box.

Here's a very typical case in point. consider a box containing the characters X-2. The item it's referring to has been redesignated as X-1315 along with about 100 others that require a similar change. And in other cases, insted of adding text, I am rearranging things so a frame containing 8pt text would need to resize up to 10pt. Again, this is completely manual at present. I don't mind doing ones-and-twos, but hundreds.....
It's bad enough having to edit each of those boxes, but to be required to resize each text frame individually is painstaking and something I desperately need to automate. To be clear, only boxes presentaly formatted in a very particular way (character styles for the different point sizes I use in these; 6- 7- 8- and 10-pt text).

See the attached screen grab; any text frame containing X-something (X-400, X-440, etc) will need this treatment, nothing else.