X-ray to bolometric flux ratio as a function of the Rossby number for the coronal eRASS1 sources with rotation period. The dashed red line shows the best-fit model of Wright et al. (2011) and the blue and green solid lines show the best fit of the broken power law (Eq. (10)) and the polynomial (Eq. (11)) model, respectively. The color scales with the BP-RP color and the outliers excluded from the fit are shown as black dots.