Hi,
lemme try to answer your original question:
the easiest way to use adaptive lighting (automatically adjusting brightness and color temp during the day) without relying on cloud services is to install HACS (the Home assistant community store). This gives you access to tons of user customizations that often work better / provide more functionality than HA core.
Then you search for + install the “adaptive lights” component GitHub - basnijholt/adaptive-lighting: Adaptive Lighting custom component for Home Assistant
Voila - you can now configure your adaptive lights via gui - check the documentation or just follow the video tutorial here: https://www.reddit.com/r/homeassistant/comments/jabhso/ha_has_it_before_apple_has_even_finished_it_i/
Other (less recommended) options for changing your lights automatically dependent on the daytime are Flux (in HA core) or the “Cicadian Lighting” custom component
Good luck