Position of TOI-2196 b in the mass-radius diagram. We also show mass-radius relationships for dry planets with different core mass fractions (Brugger et al. 2016, 2017), water planets with varying supercritical water (SW) contents (Mousis et al. 2020; Acuña et al. 2021) and Earth-like cores with different H/He mass fractions (Zeng et al. 2019). We assume equilibrium temperatures of 1200 K and 2000 K for water planets and rocky planets with H/He atmospheres, respectively. Dashed lines indicate an extrapolation of the SW relations beyond their valid mass ranges. The lines for Earth, Mercury, and 100% core are lines of constant composition of respective type of planet.