I don't consider myself huge by any means, but I'm willing to share my experience since you consider anyone over 100 subs to be eligible.
I have an okay Twitter presence (and less so on Instagram, 1,150 and 460 followers respectively), and marketing my webcomic on there has drawn a lot of success. While I don't have a huge following, I have a lot of mutuals who are very supportive and like to engage with my artwork and comic, so it seems to get seen by more people. That support bled over into Tapas where they support me by leaving likes and comments. People say they really like my artwork and that I write relatable, dynamic characters.
The other (really big) reason for my subscriber count is that I've been featured by Tapas 3 times. The first time, I was featured as a community pick and gained about 70 subscribers. A month later, I was featured as a staff pick and got about 100 subscribers. Currently, I'm featured in the Women's History Month collection and I've gained about 50 subscribers so far. Most of those subscribers have been lurkers as my like/comment rate never increased.... which is totally fine, by the way! I'm just happy people are interested enough to click on my comic.
I genuinely think my journey to success happened because I found a small group of people that I just click with and we've been immensely supportive of each other! A handful of people can make amazing things happen, like the friend who recommended my comic for a community and staff pick. Without that, I probably would have a fraction of the engagement I currently have.
Also, despite having just talked about numbers for 3 paragraphs, I'm not actively worrying about whether or not my webcomic is successful numbers wise. Ultimately, the only measurement of success I often think about is if I'm having fun with what I'm doing. Maybe that translates into my work.
Not that numbers aren't a great hit of dopamine though...!