Interesting, you shouldn't need a phone layout for the "text Format" to apply when reaching the breakpoint. To confirm, within Text Formats you have indeed set a different px size:
Screen Shot 2021-09-21 at 5.10.28 PM.png
And then within the text element you have indeed applied it to the Text:
Screen Shot 2021-09-21 at 5.12.48 PM.png
Just to get a better understandig before moving forwards - i agree with you that Custom Code shouldn't be needed 🌝
Talk soon Jordan and have a wonderful day 🏖 Richard