Pores
Pore size is largely genetic and cannot be permanently changed. What you can change is how visible they are — pores look larger when they are congested with oil and dead skin, and smaller once cleared.
Clearing congestion
Regular exfoliation is the most effective step. Clearing the buildup inside the pore makes it contract visibly, which is where most of the improvement comes from.
Cleansing matters
Sunscreen and daily pollution both settle into pores. Thorough evening cleansing prevents the congestion that makes pores look enlarged by morning.
Be realistic
No product closes pores permanently, and anything claiming otherwise is overselling. What consistent exfoliation and cleansing will do is make them noticeably less visible.