Can kissing a child on the top of head transmit cold?

Kissing a child on the top of the head will not transmit the common cold or any respiratory/airborne infection. Although some bacteria or virions might adhere to the hairs (for example in case of head lice), the common route of viral infection transmission is from the mouth/nose/eyes, with the viruses spreading during talking, coughing, sneezing, by touch through eye rubbing and similar.