Does tire pressure effect speed

Kinda-sorta.

The tire pressure will influence the actual diameter of the tire, and for a given engine rpm/gear, a bigger wheel will give greater speed, and a smaller wheel will give lesser speed.

A wheel with higher pressure will also roll easier than a less inflated Wheel. This means there will be a tiny bit of power available to make the car go faster if the tire pressure is higher.

In reality, this is all fairly unimportant outside a race course. Excess pressure will caue the tire to wear faster, and unevenly. The ride will be bouncier and handling poorer. And unless your engine is powerful enough, you won't get any use of the bigger diameter either. It'll just rev a little lower, giving you the same, or less top speed.