mistlands are the first such biome that cannot be found near your spawn -- but basically the world in V (all the worlds, all seeds that is, so YOUR world!) is a flat circle where your spawn is about in the 'center' of it, where you hang your boss heads I mean, that is your 'spawn' point. From there, you can sail a good hour in any direction and still be on the map even at top speed.
for every map, the meadows, forest, swamp, mountains, and plains can all be very close to your spawn point.
about a half hour of sailing away in any direction, the mistlands start to appear. Some maps you can walk to it on your starter island, if it happens to be gigantic, but its not normal. Most maps, you just need to set sail prepped for a long journey and with a portal you can get back home in your bag and at the home.
The other two major biomes, ashlands and deep north, are at the north and south poles and rather close to the end of the map in those directions. I recommend not exploring them much as that will block out areas you can't use when the biomes update in the future, but you can dip a toe in.
if you think roughly of 3 concentric circles around your spawn, then, the first circle has up to the plains, the second circle adds mistlands to that, and the final circle replaces most other biomes with ash/ice in the extreme north/south poles.
Its not the same as checking your map, which you may or may not want to do online, but its a very crude guide that will help you find these areas.