I've suffered from similar problems (anxiety/ADHD/compulsive behavior). Definitely had endless scrolling mess with my sleep and exacerbate mental health issues. I've tried Apple's Screen Time feature, but found it far to easy to bybass. Until they fix that, here's the system that's worked consistently, if imperfectly, for me:

1. Download Apple Configurator and put the phone in supervised mode. This will require you to wipe the phone, so make sure you have contacts, photos, etc backed up. Configurator will allow you to block apps you couldn't otherwise delete like Safari and the App Store. 2. Create a profile on Configurator and whitelist the websites you are allowed to visit. For me, this is mostly just login pages for various apps that use a webview for sign in. 3. Install Focus (heyfocus.com) on your mac. It'll take some tweaking to get the settings right, but it'll allow you to set up a scheduled blocker for various apps/websites. I have the Configurator app blocked during all but a short window at the beginning and end of the day.

This has allowed me to pare my phone down to the essentials. It's annoying from time to time, but it leaves an escape hatch for situations where I've needed more capability on my phone. Been using this for about three years and it's mostly worked.