I'm sitting at 9k followers right now and I grow at about 1-2k followers/day at the moment. My video suddenly got shown to a wider audience. I'm from a tier 2 country and my first 2-3k followers were 90% from my country, now I'm getting views from all over the world. There are no CTAs in the videos itself but I try to drive traffic to my Instagram page by linking it to the TikTok page, using a CTA in the bio, and leaving a comment on the big video telling everyone about my IG. This actually worked wonders for my IG page and I'm getting traffic. I'm soon to build a website for the brand as I see this grows pretty nicely.
Edit: This is for people that are not on TikTok yet: Can't stress this enough. If you're not on TikTok right now, you are missing out on some insane free traffic in a not so competitive environment. My videos rank for really hard to compete on IG hashtags with ease.