There are countless methods you can use to grow your brand on both the platforms.
There's been a spate of bots and growth services (see more here: https://www.growthboost.co/blog/buzzoid-review/) getting shut down by Instagram and, at times, they can also affect your account.
Here are a few of the best strategies for organic growth on Instagram.
Partnering with other accounts to do cross-promotion. This was referred to as S4S in the past but with Instagram limiting views, it may not be as effective today.
You can run a followers campaign depending on your budget but just know that it takes quite a few followers to make a meaningful impact and you may be better off focusing on organic growth channels.
Upload consistently. Of course, everyone knows this but try and aim for every other day at the least. Once a day if you can. It's social media so things move fast.
Focus on an intermediate action. Instead of buying now, it may be better to run a direct response lead gen campaign.
Videos are still getting great reach on the platform. Stories are even better. If you can get in your IG stories every day then you'll be in a really good position to engage with your audience and drive meaningful revenue.
If it can't be you then get a dedicated person to do it for you. Try to mix it up. Engagement posts like polls and the lifestyle your business champions should be more prominent than advertising focused content.