Well... it is not an easy road. I've been on social media since 2015 and just now I'm close to reach 1000 followers on instagram, but I gotta tell you... in most cases the number is for decoration, you should try to focus on having people who trully interacts with you, commenting, liking, sharing your stuff.
If you're posting as an artist for less than a year then don't expect to grow immediatly out of nothing, this takes time and interaction flow can vary depending the week, the day, the hour, etc. Try to focus on building your brand instead of focusing solely on numbers, what I mean, having work done, if you don't have much to show then no one is going to stay much to see it, ake sure to always have a new product, at least 2 per week.
To promote yourself properly you gotta do the main stuff that is posting daily, some sketches, some wips, finished works, time-lapses. comic strips with relatable stuff, doodles, whatever that gives the impression that you're active and constantly creating stuff. And from that, make different content like fanarts, original art, challenges, prompt lists, etc.
The second in line of priority you gotta do is make friends, or at least active interactions with other creators & the followers you already have, STILL, make sure that these interactions are genuine, otherwise it won't work and you'll feel tired of faking and ghosting can lead to others to unfollow you. (And this is also why doing follow x follow doesn't work in most of cases)
Then, I would highly recommend doing the main three:
Facebook - Instagram - Twitter
Then you can have additional ones such as Ko-Fi, Tumblr, Discord Servers, FB groups (Around 100 helps), etc.
Always using their respective hashtags, checking their algorithm to know what works, if videos, if images, different times of the day.