They are totally necessary - if you don't use the same passwords across the internet I mean.
How many accounts do you have on the web? I can count at least twenty accounts that I have and use from a variety of services. Keeping different usernames, emails (through alias) and passes in mind is no easy task, so a good password manager is absolutely needed.
People are recommending Bitwarden and I can't say it's bad, truly, it's a really secure and private alternative. Although, in my opinion, keeping a offline safe for your accounts is way better because only you have the absolute control over all the credentials. I use KeePassDX on my PC and phone, synced by Synching, and being loving it for some years still.
I'm kinda surprised that didn't see anyone recommending RethinkDNS. It's a DNS and Firewall app that works through VPN. You can choose through a bunch of servers that they offer, including the RDNS Plus that you can select the blocklists you want, or just chose other DNS of your choice and block the domains using local blocklists in the app. Using the firewall function, you can block or allow individual domains or apps. Been using it for like two years.