Good news -- you can do this too! https://github.com/actions/stale
Seriously, auto-closing issues that haven't seen activity in 3–6 months is one of the best things you can do for your project.
If nobody's touched it in that long, it's time to accept it's never getting prioritized -- it's just collecting dust and making your backlog feel way heavier than it actually is.
So let it go. Let it go! (It feels good to channel your inner Elsa!)
A clean backlog is a healthy backlog. You'll actually be able to find the stuff people care about instead of wading through years of noise. And if something truly matters? Don't worry... those issues come back, they always do.