
To your first point, that's more realistic to the time. The nobility didn't do hard labor and there was a period of time where a man was at his most attractive when he became out of breath trying to tie his shoes. As the prince, he likely had to participate in swordplay to understand the ways of war. However, that amount of exercise will not outdo the diet.
Not entirely the time we are talking about but Henry the VIII and his court regularly ate 5000kcal a day with practically no fiber. He's a great example of this because he used to be very active and athletic as a young man (because he wasn’t supposed to be the heir) until he suffered a leg injury that slowed that down significantly.

Frfr. Although you can’t exactly say that Korean manhwa is historically accurate lol they just romanticise historical western culture
In this case though, looking at the dress styles and stuff this is definitely set in the Victorian era. You can see that BOSS BITCH MOMMY’s dress looks very Victorian esque. If you search up a pic of queen Vicky you’ll definitely see the similarities.
Honestly I think it’s just more the art style but yeah one of the things I love is how her parents look because they look like actual parents not hot teenagers who look like they could be protagonists themselves
1) EVERYONE LOOKS SO SQUISHY (I LOVE THE HIGHLIGHTS) IT MAKES SEXY TIME LOOK SO SMEXY TOO
2) LOVE MY FL, LOVE HER TO BITS I COULD SING HER PRAISES EVERYDAY AND I FR 100% UNDERSTAND THE CROWN PRINCE WHO WOULDN'T FALL IN LOVE WITH THAT GIRL YOU SEE IN PUBLIC EVENTS WHO IS ALWAYS BEATING HER INCOMPETANT PARENTS
3) Crown prince has good taste, and he's breedable and submissive