Ive taken time to poke at tags, so here's some tips:
Don't use only the most popular tags. The art will vanish in an instant and you'll only get seen by people who avidly scroll through them.
Try for tags with posts between 10k-100k for most of your tags. Then throw in some of the huge ones.
Don't use the same tags twice in a row. Even if it's relevant, the algorithm is made to nuke bots and content farms, so you're asking for a shadowban.
Don't post EVERY day, but stay active. Post stories daily and interact with other posts. Behave like a regular user. The algorithm rewards it.
Share art from other people while expecting nothing in return. It gets their attention and it shows you're a community player. (I have a weekly event called #sharechainsaturday if you all wanna check that out.)
Give your potential followers something to get out of following you. Story content, merchandise, art tips...instagram is a platform of "what can you do for me" if the answer is "i can advertise my webcomic weekly and thats it" you'll not do too well.
Make friends! Comment on posts. Reply to stories. Get in as many dms as you can. You'll find the artists there, even the huge ones, love to chit chat.
When you post, be active. Go to the tags you just posted about and comment on things and like other things. You have to put yourself in a community on instagram before it will reward you in that community.
Only post things you're gonna post more of. My post with catra is terrible cause i never draw Shera fanart. People found me, sure, but not a lot of them followed. Be yourself, they won't reward you for being trendy unless being trendy is your thing.