Would a larger pressure tank give me more pressure

Maybe yes, maybe no. I assume you're asking about an air tank, which is used to drive air-powered tools such as nail guns, impact wrenches, etc. It depends on whether the air pump can replenish the tank as quickly as you draw air out. If it can't, then in general the pressure from a small tank will drop off quicker than for a large tank as you use air.

I'm sorry but should have stated that I was asking about a ater well tank.

In what context is that? Is it something like you have a water tank on your house and would like to get higher pressure in your taps?

If so, then the pressure will be bigger if the tank is higher, and when there is more water in the tank.

The pressure depends on the depth of water (or height) and the higher the depth/height, the greater the pressure.