Late night theories on the four brothers' height and Kronos,
Kronos is shown to be much bigger than Zeus, who would already be a sort of giant himself, but maybe Zeus' gargantuan form was just him emulating Kronos in the vs Adam fight
According to the SnV height chart, Ares is 240cm / 7'10" lol wtf, and Zeus in his weird Kronos' form is probably about that size, but when he was down to regular size, he was probably between 195-200cm / 6'4-5" because he shrunk to 160cm / 5'2" in old age lmao. Meanwhile, Poseidon is just 195cm / 6'4" and I think Hades will be around Poseidon's height as well, though we have no confirmation as to Adamas' height. I believe it would make more sense if the brothers were a more evened out height when "normal"?
The Kronos below would definitely be able to swallow his children, but I'm not so sure about maintaining them in his belly well into teenage years lol maybe, but it'd be a tight fit for them
Furthermore, as children, Adamas and Poseidon have been shown in an actual building, in different settings, not what we would probably consider Kronos' belly. SnV does not actually mention that Kronos swallowed his children, but Zeus has said he was a bad father, so assuming it follows the original myth and assuming he did, here's what I think is the case:
Hades, Adamas, and Poseidon were not physically swallowed, but are imprisoned in time, locked away in Kronos' palace / his "belly" -this is because Kronos fears one of his children will overthrow him as he did Uranus by participating in the Titanomachy.
Basically no children out of the palace = no participation in Titanomachy, the end.
BUT Rhea tricked Kronos into thinking Zeus is there, and hid Zeus away on Crete, where he was raised by his foster mother.
The Titanomachy Tournament comes up, and Zeus appears as exciting as it may sound, we would not have cupbearer in disguise Zeus or Kronos throwing up his children.
Zeus is the only one of Kronos' sons who can participate in the tournament.
Kronos recognises Zeus because come on, they kind of look alike and Zeus proceeds to defeat him, after which Zeus goes to set his brothers free and the rest is history (ie. they draw lots for their domains).
Anyways yeah I've just been thinking because I want to write my fic and there's no proper source for these things so we're left to fill in the holes ourselves, but I would love to hear more people's takes on this!