Q.Small Fruit on tomatos
I have small fruit on my tomato plants, they are growing in pots will that make the fruit small?.

First make sure what variety of tomatoes that you are growing. Check the labels or seed packets for fruit size.
Watering is the most likely issue for fruit not growing.
These links will help you.
https://www.gardeningknowhow.com/edible/vegetables/tomato/watering-tomato-plants.htm
https://www.gardeningknowhow.com/edible/vegetables/tomato/growing-tomatoes-pots-containers.htm