What are some effective products or treatments for skin whitening?

As I get older, my skin seems to be getting duller.

It seems like I'm getting a lot of freckles and blemishes on my skin.

There are a lot of advertisements for products that claim to be good for skin whitening, so I was curious if they actually work.

I was also curious if dermatology procedures really have a whitening effect.

And do I need to continue receiving dermatological treatments consistently?

I was also curious if my skin would become dull again if I stopped the procedure midway.

If you have seen results from any skin whitening products or treatments, please share which products or treatments were used.