The distance $D$ to an exoplanet system with imaging and spectral measurement can be obtained by using the orbit as a ruler. The measurement of the Distance to a typical exoplanet system with imaging and spectral measurement can be accurate to $\delta D/D\sim 0.2$, if the orbital velocity of the planet can be accurate to $\sim 3 {\ \rm km/s}$.

https://chinaxiv.org/abs/202307.00280

Qian, Lei.(2023).The Distance to Exoplanet Systems with Imaging and Spectral Measurement.中国科学院科技论文预发布平台.doi:10.12074/202307.00280V1