Big cars on tiny engines?

Admittedly I am a bit thick but bear with me. I am looking at the Skoda's like, https://www.arnoldclark.com/used-cars/skoda/karoq/1-0-tsi-se-5dr/2020/ref/arnat-u-76942. Nice looking cars but the 999cc engine is surely woefully small?! My son's VW UP is half the size, same sized engine and ok until you load it up with fatties like me or try driving over some hills. Is anything under 1.5 l going to feel absolutely flat?