Pressure would be the same in a static (no-flow) situation whether you had a soda straw or a fire hose. WHen you then start to draw water, the friction along the way will cause the dynamic pressure to drop. Smaller pipe causes more restrictions/friction, and at the same volumes, will have lower pressure. now, without knowing what pipe and how it is run, cannot give you a pressure drop calculation. The more pipe it has to go through, the more friction, the less pressure and therefore volume available at the end.
The Bernoulli principle effectively says, a short restriction causes the fluid to speed up, then it will slow down again after that restriction. It does cause a bit of friction, but depending on how long that restriction is, it may not cause much measurable volume/pressure change outside of a laboratory. It's there, you may not notice. Make the restriction longer (say a 1/2" pipe between 3/4" ones), and you certainly will notice the flow reduction. FWIW, at the same pressure, a 3/4" pipe will carry twice the volume of water as a 1/2" one. You may not need it, but if you do, a larger pipe is called for. Running water faster than design creates its own problems of pressure loss, noise, and pipe erosion.