Can anybody explain how to discover new features of one ui 7.0 in galaxy A35樂

Before my phone given to a service centre, phone is amazing, after collecting it from the servicing centre my device started hanging and the entire phone got damaged as picture quality reduced, mic is not working as well as speakers are not workin...

Original 25mp front camera picture #a50Edited picture

Place of beauty.Captured - GAlAXY A50