The first half is most of the game, and the part first time players will find themselves spending the most time in. Exploring the world, doing side quests and exploring every dungeon.
Then the second half is preparing for the end game by entering the capital. Many first time players will hit this part thinking its the actual end game, and this is where burnout occurs once they realize they still have a lot in front of them, and their choices start mattering in the story. My first time I accidentally triggered the chaos path before hitting the last boss in the city, and it made the buildup very awkward.
The third half is the actual end game.
I'm wrapping up my second half of my second play through, about the enter the third half. This game is huge. it's much bigger than BotW or TotK. Every hour I spent in TotK last year I kept thinking to myself "I'd have much more fun in Elden Ring" and it turns out I was right.
That's not to say TotK is a bad game, just a different one in the same genre. TotK feels far more empty though. Elden Ring is littered with tons of hidden nooks and crannies, and tons of little bits of environmental storytelling. From are very big believers in show, don't tell.
I think the biggest difference between the two is TokT is trying to tell you a story, Elden Ring is about a story that happens to you, if that makes any sense.
I still think I prefer the tight world design of a Dark Souls compared to the vast openness of Elden Ring.