Do Instagram paid shoutouts use bots?

I started a new online store and am using Instagram as my main social media channel. I've been trying to grow my account as organically as possible and it's going well, I'm seeing ~5-15 new followers per day and decent engagement.

I have been looking into doing paid shoutouts in my niche but wasn't sure how to find the best accounts to approach to do that. I decided to pull the trigger and try it out with an account that has ~100k followers. After they posted my shoutout I got a huge influx of new followers all one right after the other which seems really fishy to me like they are bots. I'm talking like 250 new followers in the span of an hour. I don't think that's normal? Now I'm pissed cuz I feel like I need to go through and eliminate all the bot followers.

My question is- Is it possible for those large accounts to basically hire bots to follow you? I thought that was only possible to do to your own account. How does that work? And any suggestions for getting rid of them now? Also has anyone had success with or found legit accounts to do paid shoutouts?