Will the melasma treatment be effective on cheeks that have darkened after being exposed to a lot of sunlight?

I am wondering when would be the best time to start melasma treatment, as the brownish tint around my cheeks has become more visible after spending a lot of time outdoors or going out during the summer. Even though I usually apply sunscreen, it is difficult to constantly reapply it while out, so it seems hard to completely avoid the effects of UV rays.

At first, you might think it is simply a slight tan, but if the discoloration remains in certain areas even after time passes, you might wonder if you need other care.

Can I expect melasma treatment to be effective even on skin like this? I am also wondering if I need to check if my skin, which was irritated by UV rays, has sufficiently stabilized before receiving treatment. I would like to know if it is better to look into laser treatment immediately once the pigmentation has darkened, or if it is better to monitor my skin condition for a certain period before making a decision.

I am wondering if there is a possibility that the pigmentation will darken again if I continue to be exposed to sunlight frequently even after melasma treatment.

Besides reapplying sunscreen when going out, is physical protection such as hats or parasols also important? I am looking for a long-lasting care method that considers both treatment and prevention.