From many youtube videos I watched, 'rides' sounds like 'rise', 'roads' sounds like 'rose'. My question is, are native speakers drop the 'd' sound when followed by the 'z' sound? If not, what is the difference of [dz] sound and [z] sound in terms of tongue position?
The pronunciation is similar but different. There is at least a momentary closure of the airway by the tongue when saying "rides" or "roads". However when saying "rise" or "rose", the consonant is fricative, and the airway is never completely shut.
The words "rise" and "rides" function as a minimal pair, and the ability of native speakers to distinguish these words is evidence that they are pronounced differently, even if you have difficulty telling them apart.