What’s ‘In’ for 2024? In-and-Out Lists, Apparently.

Extra-large bags, silver jewelry and gardening are in. Quiet luxury, podcasts and late bedtimes are out. That’s at least according to Instagram and TikTok, where lists confidently declaring which trends will thrive and which will die in the new year abounded as the clock struck midnight on Sunday.

The dead week between Christmas and the new year has always been conducive to introspection, the hours usually spent working or socializing suddenly freed up for stewing in regret, rethinking bad habits or planning a comeback. But instead of making traditional New Year’s resolutions, many TikTok and Instagram users have started publishing “In and Out” lists that mix predictions of what will and won’t be considered cool in the coming year with aspirations for their 2024 selves.

“I feel like New Year’s resolutions are very personal, and an In-and-Out list is a more niche, general statement,” said Lukas Battle, a stand-up comedian and TikTok personality. “It’s also a way to make fun of last year’s self and set a goal. For example: OUT: being in a toxic relationship, IN: hanging out with friends and going to dinner.”

In-and-Out lists are particular to their makers, incorporating personal tastes and beliefs, sense of humor, and informed (or uninformed) predictions to create a vision for the year ahead. Some items on the list are actual fashion or culture trends — like animal prints or espresso martinis — while others are more behavior-oriented. Common ins for 2024 include early bedtimes, staying hydrated and red-light therapy, while impulsive shopping, mindless phone scrolling and vaping are popular outs.

Kit Keenan, an influencer who describes herself as “a young Martha Stewart stuck in Blair Waldorf’s plotline,” posted a TikTok video last week in which she interviews her mother, the fashion designer Cynthia Rowley, about what’s “In vs. Out” in the new year. The consensus? Knee socks, prep school and animal prints are in; capri pants are decidedly out. “If you’re not Bella Hadid, I don’t want to see you in capris,” Ms. Keenan declared.

In Mr. Battle’s own In-and-Out list, he anticipated the end of “quiet luxury,” the trend in which wealth is telegraphed in a stealthy way. Instead, he intends to replace it with “loud budgeting,” which he says is “all about not being weird about money, being able to communicate about it to your friends and really be like: ‘I don’t want to do that. I don’t think that’s worth my money or time.’”

Mandy Lee, a professional trend forecaster who has predicted the rise of phenomena like indie sleaze and balletcore, also made an In-and-Out list, which she posted on her Instagram account. For her, the lists are less about making serious and informed predictions about trends, and more about low-stakes fun with friends and followers.

“It feels more like people’s personal manifestation rather than what they actually think is going to be trending,” Ms. Lee said. “I put deviled eggs on my In list because I made deviled eggs on New Year’s. Do I think delivered eggs are going to have a resurgence? Honestly, maybe — but there’s no real data points or evidence pointing to that happening.”

Certain subjects have shown up on multiple In and Out lists, which may give at least some idea of what people think will be cool in 2024. Minimalism, for example, is pointedly out, being traded in for wild animal prints, bold color and enormous logos. Bows, the sartorial embodiment of the girlhood trend, are also on the way out, along with Snapchat, oversharing and the clean-girl aesthetic. What’s in? Sobriety, putting your phone in Do Not Disturb mode, polka dots, cherry red, dinner parties, outfit repeating, having a nemesis and drinking soda, to name a few.

Some things appear to be In and Out at the same time. Perhaps no item is more controversial in this year’s In and Out lists than oat milk, which appears on as many In lists as it does Out. But Mr. Battle says there’s no gray area here. “Oh, oat milk is definitely out,” he said. “It’s out because someone at a party told me it was unhealthy.”