I have seen this behavior on different cards but for the sake of clarity, I’ll explain my experience with Atomic Calendar Card.
I have configured the calendar card with card mod to increase font size. This looks good on my PC screen and on my mobile but the font size is much smaller on the TV (from Chromecast) and on Google Nest Hub. I tried increasing the font size in the card mod but the font size is not increasing on the TV/Chromecast. Why this inconsistency between devices? Is there anything I can do to overcome this?