I’m assuming you mean for the sunset watch face?

go to automations

time of day (sunset, daily, run immediately)

new blank automation

add set watch face, set to an analogue face you like

add set silent mode, make it turn on

hit done

then again, automations

time of day (2 hours before sunrise, daily, run immediately)

new blank automation

add set watch face, select your day time face

add set silent mode, turn silent mode off

new automation

daily at sunset

then new blank automation

then search watch for what you want

focuses are fine, I use them too for work, gym and sleep but the sunset/sunrise can’t be attached to a focus and I don’t like the icon there when I am home/doing my weekend errands.