I’m using LogSeq now for such a long time, I’m surprised it seems this didn’t come up yet in the issue tracker and here, and it is related to requests like Turn "dark" theme into "logseq" theme and add proper dark theme, yet may come to a different conclusion.
Which brings us to the point. In fact,
as a LogSeq user, I need to set different themes for night and day, in order to benefit from a writing experience that is customised to my visual convention throughout the day.
Sometimes the dark variant of a theme isn’t adapted at all, or the theme is already only a dark one, and I would like to accompagny it with another style that suits my usage better. For some, as in the post above, this can be a Black theme, and for others Sepia during the day, and Dracula during the night.
Maybe a mischevious filter could even allow to select which variant (day, night; is it even possible to consider more, like with font styles?) of a theme I would like to have applied by preference.
This way I could use a dark, if any, theme variant during the day, and a light, plus maybe possible others, during the night, if I would like to do so.
Some operating systems will sync their dark mode setting based on time. I think I saw that as an option in Ubuntu. If you configure Logseq to use the system setting, maybe that will achieve what you are looking for?