Hi Eduardo,
Thank you for the contacting syncfusion support.
#Regarding dark theme support
we would like to inform you that you can achieved your requirement by using button click event to change mode into dark mode to light mode and light mode to dark mode in SfSchedule. we have prepared the sample as per your requirement and attached in the following link for your reference.
Please let us know if you have any concern.
Regards,
SaiGanesh Sakthivel