What does it actually mean when the 5G chip comes from a 7nm fab instead of a 5nm or 3nm? Does the battery have to weigh 1g more to supply the chip with the ext

What does it actually mean when the 5G chip comes from a 7nm fab instead of a 5nm or 3nm? Does the battery have to weigh 1g more to supply the chip with the extra power and the phone have to be 1mm³ bigger to accommodate the bigger chip and battery, or will the numbers have be bigger? I opened an old phone when I replaced it a few years ago, and described each part to my children. The chips didn't account for much of the volume. I realise that a 3nm chip uses less power for the same processing than a 7nm chip does. Phones are mostly idle, though. Can receive/transmit 100Mbps or whatever, do receive/transmit very, very much less. I'd be thankful if someone who really knows about phone geometry/power could explain.