Yes, chapters look at your Instagram. Not with a magnifying glass and not with a scoring rubric, but members are college students and looking people up is what college students do. Here's the cleanup that takes one evening.
The obvious pass. Archive (don't delete, archive is reversible) anything with alcohol if you're underage, anything you wouldn't want screenshotted into a group chat, and anything mean-spirited, even as a joke. Check tagged photos too, that's the tab people actually judge, and you can hide tags without drama.
The subtle pass. Your bio: real name or recognizable version of it, your school and year if you're comfortable. A private account is completely fine, but a private account with a blank bio and no identifiable anything reads as a ghost, and members can't get lightly familiar with a ghost. Some visible personality helps you, whether that's a public account or just a bio that confirms you're a real incoming student.
What to add, not just remove. This is the part everyone skips. Two or three posts that show your actual life, your friends, your dog, your senior trip, whatever's true. You're not building a brand, you're giving a 20-year-old something to open a conversation with. "Wait, I saw you ski, where do you go?" has started a hundred real recruitment conversations.
What not to do. Don't follow every chapter and comment on everything, it reads thirsty and chapters notice. Don't post recruitment countdowns. And don't wipe your account to zero posts, a freshly nuked profile is more suspicious than a normal messy one.
The standard isn't perfection. It's "would I be fine with a chapter's newest member seeing this," and for most people that's a 30-minute archive session, not a crisis.