Thinking about the gwerin (high elves). So many of their "stock" traits were cultural (and part of the base elf) that splitting them out left them rather...sad.

Gwerin have the following differences from other elves in my setting:
1. Gwerin are strongly associated with wizardry and arcane magic in general. Their direct ancestors developed it, and they've been breeding for arcane power (directly or indirectly) ever since. In fact, this was the point of departure (thousands of years ago) between the gwerin and the ihmisi--the first imhisi were culled from aelvar (as the parent race was called) society because they couldn't/wouldn't/didn't want to learn arcana. This split the race into gwerin and ihmisi and directly led to the ihmisi creating druidic magic and using it to drop a moon on the aelvar empire that rejected them.

2. Gwerin used to be the longest-lived humanoid race by a lot, living to over 1000 years. This changed about 250 years ago, dropping them down to 200 years (still the most, but not nearly by as much). They still don't show visible age very much (maturing at normal rates but having a prolonged "adulthood" until they're a few years from (natural) death).

3. Gwerin are not associated with the fey at all. The origin of the aelvar race is with the lucians, who became the inhabitants of the astral plane.

4. Gwerin are not reincarnated at least as far as anyone else knows. None of the Mordenkainen's Tome of Foes lore is in play.

Since I'm speaking strictly biologically here, giving them a cantrip/spell doesn't work...unless they're racially all sorcerers. Which is possible. But they're associated much more with INT than with CHA, and INT-based spell-casting is learned, not innate, so...

Trance/meditation (and associated lack of need to sleep as most understand it) works IMO--it ties into #3 and gives them an otherworldly edge. So Superior Trance (downgraded to Trance for the other aelvar descended races) is in. But rather...ribbon-y.

So what about something like:
Innate Spellcasting. Generations of breeding for arcane mastery has granted the gwerin an innate sensitivity to magic. You can cast detect magic without needing components. You can use this a number of times equal to your proficiency bonus, regaining expended uses when you finish a long rest. Starting at 5th level, you can cast dispel magic once with this trait, regaining the ability to do so when you finish a long rest. Intelligence is your spellcasting ability for these spells.

Both of these are entirely innate spellcasting, representing less spellcasting than just a heightened natural ability to sense and cancel magic.