I have an acoustic guitar that wasn't mine originally and when I decided to change the strings I also decided to change the bridge pins. Do they come in different sizes? Because the ones I got seemed about the same size as the old ones, and the old ones were pretty hard to get out. I thought you were supposed to get them the same size. Should bridge pins be easy to slip in and out? I don't want to break my guitar's bridge
Bridge pins are tapered. Most things engineered with tapers are for a purpose - to remain a snug fit. Once in place, they bind, and are not so easy to remove. That's the realm of parallel sided objects.
As the pins go in, they get tighter and tighter. Added to which the ball end of the string jams them in. Then if they're in for years, they don't like being ousted, so will be tight - usually.
A lever will remove them safely, after some fiddling. In my experience they are all approximately one size, although occasionally new pins won't sit as low as the ones they replace.