I find that I’m more engrossed in a story when there’s not a whole lot of world building being thrown at me in the introduction. It’s rather jarring to have somebody explain the lore of their story when I haven’t even met the main characters and I can’t make a connection. A tiny example that I have of bringing a reader into a pre-made world is by having a short conversation with an important npc during dinner, or something.
For example, it could be you and your best friend having a conversation that helps the reader get a little background on your relationship with them without explaining it:
“I suggest that you stay away from the manor when conducting your experiments, Evan. I have suspicions that the Caretaker has bewitched the statues and portraits now that you’re back.’
Evan scoffs. “We were children when I broke that window! That was twelve years ago, and I wasn’t as well-educated at the time. I’m older now. My inventions are rarely as catastrophic in nature.”
“It was far more than just the window. You took out the entire floor and wouldn’t have survived hadn’t it been for your shielding.” Evan let’s out an indignant huff but doesn’t argue the comment, and his darkening cheeks speak volumes. “So please, Evan, for me, you must tinker with your inventions in the old workshop. This place is very special to our families. Even Father swore that nobody had caused such damage to the manor since the Great War ended four centuries ago.”
Things like that. Playing it subtle enough for the reader to pick up on the fact that Evan has made an enemy out of somebody who can bewitch inanimate objects, he’s an inventor who you’ve known for at least twelve years, he has the magic to shield himself, the MC has a father who is likely alive and that there was a Great War.
Stuff like that.