Hey there and welcome to the Samsung UK and EU Community Customer to Customer Forum
Before you posted, did you search the forum? This question has been answered so many times.
Within the first 14 days, your device will go through a learning process to learn how you use your device. It will then optimise your battery settings.
Depending on how you use your device, post optimisation expect between a full day and for light usage up to a couple of days on a full charge.
S24 Ultra