There are some scheduling tools out there such as Buffer. You wont compromise a new account because buffer isnt a automation tool is simply sends you a reminder to log into their site and send a IG post. I tried this and it my sound lazy but i got tired of constantly logging in to post something specific.
There is an app i used to use back in the day, i think it was call Captivate, on the itunes app store. it allows you to select the followers of an IG account and follow their followers. For example you could follow all the followers that follow the NBA Instagram page. It will automatically follow them and you set the amount of people you want to follow.
The downside of this app is that you need your phone plugged in as once it locks the app times out. So i used to follow people when i was asleep with my phone plugged in at night. They also have an unfollow tool. So I would spend 2 days following, then 2 days unfollowing. On everage, i would get about 20-50 new followers a day.
If you want a head start you could also find a trusted account seller who sells accounts with followers grown from automation. Ive done it a few times and its worked out. If you know how to take care of the account after the handover process so IG doesnt realise then the account will keep growing and wont raise any flags.
I think FuelGram might be a great fit for what you need as that tool is quite niche-oriented. If you start using it, you’ll be placed inside a group relevant to your account’s niche and, once within it, you’ll start to exchange likes and comments with them via an automated process.