By using Card-mod !
🔹 Card-mod - Add css styles to any lovelace card.
And the Search Box in this Forum can also be used to search in the whole Forum, or in a Specific Topic, like i.e above
Search results for 'justify-content; stretch' - Home Assistant Community.
Beside, Various cards have various options, as as all custom:-cards are build by individuals, they are build different, and behave different. ( Some dev’s of custom cards specify width in (px), in the card.js, some with “max” etc. etc. )
If you have a use.case ! , with a specific card, i suggest you ask/search either in a Topic for that card, or in some of the big card-mod Topics
But as you mention specifics, within a card (fonts, icons etc) , you will have to read and test alot, upon your big-tv screen, Fonts / Pics are often specified in px.
But to be honest, i have no “issues” with the scaling on various devices
from Mobile(Max 900px), to laptop (1366x768 ), to TV (1920x1080 )
And you haven’t “shoved” anything, or mentioned how your Browser is connected to your big-tv ( You do know you can specify i.e resolution , and in some case i.e text-size.( on the device/connection)
But again if you build “adaptive” there should not be any problems, as i have experienced