Usually it's just an island with one or no trees.

So this one time, I found a seed that had an EXPOSED STRONGHOLD AT SPAWN, also a ravine and a village, and if you built a portal at the spawn point, you were within sight of a bastion remnant and a nether fortress. I couldn't believe it, I was like, this is going to change minecraft speedrunning. I was so excited. I tried to beat the game.
But after ages of searching the stronghold, I even switched to creative and used cheats, there was no end portal in the entire stronghold. An amethyst geode had generated on top of the portal. I was so sad.
True story.

There is a portal in every stronghold. you must be on bugrock

There was one but a geode had generated on top of it.

I feel your pain, once I found a stronghold 100 blocks away from spawn, and it spawned like at y level 40 AND like inside a mineshaft, I had to go in spectator to find that there was no portal

p a i n

Oof man, remember the time TommyInnit was doing a speed run and the portal in the stronghold he found got cut off by one of those fossils?

They really should make it so stuff can't generate over end portals

yea they really should

Bro just search up best survival seeds on YT