There are two specific things I want to point out from my hands-off demo. First, I noticed that the Pokémon in the first trainer battle were around level 60 - the same as the highest level Pokémon in the trainer's party. Nintendo’s Demetrius Boggs told me that the new Pokémon expansion pass areas’ trainers and wild Pokémon scale with your own Pokémon's levels. Specifically, Boggs confirmed the DLC areas would even scale to match a team of Level 100 Pokemon.
Not only that, but these areas can be accessed as soon as you reach the Wild Area of Pokémon Sword and Shield, just a few hours into the games. So whether you've just started or have already completed every post-game activity and have a full party of level-100 Pokémon, both parts of the expansion pass, The Isle of Armor and The Crown Tundra, will match your Pokémon's level.
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Overall, each of these micro areas seemed to be a little more full with environmental touches like logs or trees than the mainland wild area was. I also saw Pokémon interact with their surroundings in ways I hadn’t before. For example, I saw a Pokémon on a tree branch in the forest. Though Nintendo couldn't confirm how we could interact with this Pokémon, I assume it could be lured down from the tree by whistling at it - like you would lure flying Pokémon down from the sky in the base Pokémon Sword and Shield.
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One of the challenges involves collecting Max Mushrooms, which are used to create the previously revealed Max Soup which unlocks the ability for a Pokémon to Gigantamax. Though I only saw a single different trial (one I can’t reveal just yet), it reminded me of the minigames you might encounter as part of Pokémon Sun and Moon's Island Challenge, except perhaps less involved.
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I didn't see the menus for this, and Nintendo and the Pokémon Company couldn't give me any additional information, but I saw two different bikes with different “trails" similar to the trails you unlock for your cars in Rocket League!