I know of a LOT of fics where they’re college AGE, so I’m just going to rec a few I thought of off the top of my head where at least one of them is IN college, okay? ((note: I’m saying college here as in the American usage of the word, meaning university level))
Not That Bad -> Literally my favorite college au fic. Like, if you haven’t read that one already, you should. It’s adorable, and I love the pacing, and I love the insight into both the characters. It’s just good story telling and good writing, man. It’s complete and written by the talented @blue-lancer
Sharps and Accidentals -> Everyone’s a music major of some sort, Keith is deaf, and Lance is TRYING (but constantly fucking up, but he gets there). This one is also really good. I’m a slut for fics that actually have good sign language knowledge ((any of my homestuck followers know this)). The pacing is good, the writing is amazing, and I’m probably super biased because I love @zizzani and everything they write ((Bo is also my co-author to the time travel au and Drive Like You Mean It)). This fic is still in progress, but it’s looking great so far.
So Anyway, Here’s Wonderwall -> So this is a fic that’s slow to update, but I personally really like it. It’s falling into this category because Lance is in college, even though Keith is not. Keith is the bassist of a band. I just really enjoy the writing of this fic, the pacing, the world and oc build, and the overall atmosphere. It just has this VIBE about it that’s so chill and so unique. The moments between Keith and Lance just feel so genuine and real. It’s the story of two dorks slowly falling in love, and you can really feel that in each special moment they share.
Keith Kogane’s Guide to Extracurricular College Planning -> So this one is significantly shorter than the others. Only 4/5 chapters. Everyone is in the same fraternity. And… idk, I just really like it?? It has this vibe and a take on the characters that I just really enjoyed reading. It’s about poor Keith being in love with his best friend for years, and how the two of them finally come together.
Cross-Steps -> This one is also shorter by comparison, completed, simple, and very cute. Keith is a long boarding youtuber, and Lance is obsessed. They go to the same college. There’s mutual pining, boys being idiots, and it’s just a super cute, really chill and easy read. You can breeze through it and feel all the happy fuzzy fluff feels if you’re not in the mood for anything too heavy. It’s written by @varevare!
Don’t Break Connection, Baby -> This one is making the list because Lance is in college, they’re college age, and by the end of it Keith gets accepted into college, too (spoilers??). It’s nsfw, so you’ve been warned! Keith is a sex phone operator that Lance prank calls and things spiral out of control for both of them. I absolutely love this fic, because @princedeadend does such an aMAZING job balancing humor and smut and plot. Like, it’s the most realistic smut I’ve ever read BECAUSE it’s so ridiculous, hilarious, and fluffy. I saw someone once said it’s the fluffiest smut, and honestly, that’s a good description. Wrenn has this crazy ability to move the story along and set up setting using mostly dialogue, and it’s something I admire. Definitely a fun read. Be warned for extreme second hand embarrassment in the first few chapters.
Voltron Cafe -> Okay, so TECHNICALLY, they’re not in college, but Lance is studying for college and they’re college age, so that has to count for something, right? It’s still in progress, but it’s an extremely fun read. I’m enjoying it a lot. The author, @hannahmelto, also wrote Cactus, which I really enjoyed. From what I’ve seen, they’re currently teaching in Japan, and they wanted to take a stab at writing a maid cafe au. From what they’ve said in their notes, they’re approaching this fic like a shojo manga, which I think is a really interesting writing challenge to give to yourself (from someone who loves giving herself writing challenges too), and it definitely pays off! It reads like a manga in the best way possible. If that’s not your thing, I get it, but I’m very much enjoying this fic. They also have an ask blog for this au! @voltron-cafe
Misdialed -> More phone shenanigans! Just as the title implies, Keith accidentally calls a wrong number and ends up with Lance. The two of them start a friendship not knowing who the other really is. But they also both go to the same college and have mutual friends. They don’t get along in person, but on the phone they grow close. It’s an amusing and fluffy read with a lot of dialogue (that’s not a bad thing), but @sasaina-ai has threatened angst on the horizon (also not really a bad thing). This one is still in progress!
Okay, so honestly, there are probably LOADS more “college/college age” fics I could rec, but these are the first ones that came to mind. I thought of a few others, and even though I’ve been enjoying those a lot, they haven’t updated in quite a while, and I feel bad sending you that way since I know a lot of people don’t like to get invested in fics that haven’t updated in a while.