I use hashtags, both geographic and descriptors, and I still get absolutely shit reach, both on IG and Twitter.
Then IG can shadowban people for using the same hashtags, or even by using a single blacklisted hashtag. When I took photos of my national flag, they would not appear in the hashtags I used, but only for my followers (and many of them don't do shit - took me two years to even make a hundred IG followers and almost all are inactive, it seems). IG also took down my photo of a church for no reason and my reach plummeted for three months in my first summer on IG, which was evidently a shadowban. Can also be shadowbanned for what they think is spam too. Fucked up thing is that this is done without any human involvement; it's automatic.
With the way social media have shit up their algorithms in the past few years alone, it seems impossible to grow a following with content unless one is famous already. Just as well that all free IG analytics sites have been taken down or taken over, as it would be awful to see how truly awful my reach is. I do a manual calculation of average likes and they stay single digits now. Four months since a single photo got double digits. Admittedly, I only post 7% of what I used to, pre-lockdown. My account is cursed. It would be tempting to start a new account and see the difference. There's no point though.
I took so many photos back then that I am much more discriminating now. I fucking hate IG.