Glycolic acid can help to make pores smaller but you cannot reduce blackheads, what it is is oil trapped with no oxygen getting to it, so you need to gently extract them, which are best done professionally. Always have extractions done after exfoliating, not necessarily with a peel, but a manual physical scrub can help bring them more to the surface and easier to get out. Your skin needs to be warm and soft and you should only have extractions done the same amount of time your face was steamed by your aesthetician.
Since I do my own extractions at home (and I dont like steaming my face because I have sensitive skin) I usually time the amount of time I am doing them to how long I exfoliated for.
Do not try over and over in vain to get a blackhead out. If it doesnt come out within 3 tries, move on. Your pores close ohup very quickly.
After extractions, you should always swipe the area/aesthetician should swipe area with some witch hazel astringent or an antiseptic.
And gloves should always be worn on clean hands.