From what I found, Sussex hens generally:
Are dual‑purpose: good for both meat and eggs.
Lay large to very large brown eggs, at a steady rate. Typically ~200‑250 eggs/year in good conditions.Tend to start laying around 18‑24 weeks of age.
Are hardy in a range of conditions; handle cold well, though in very hot weather need shade and good ventilation.
Gentleness is one of their big points. Sussex are docile, calm, friendly. They’re good with people, even kids.
They’re curious and foragers — so giving them space to roam or do some free‑ranging helps.