The universally accepted way is to check https://haveibeenpwned.com/
, and I wouldn't worry about those emails. Those kind of attacks rely heavily on getting inside your head. Check the website to be safe, and ignore the email otherwise.
The website is very reputable and well known among us tech savvy people. They've been around for quite some time too, something like 10+ years I think. The way I found out about the breach is because Google wouldn't stop yelling at me about my passwords being compromised, so I eventually looked into it, and for sure, I got "pwned" as they say.
BTW, I discovered a password manager that suites my needs very well! Bitwarden
. Cross platform, Excellent password generator, Free and Paid, Local program and Web Browser extensions, able to import existing passwords and logins from Firefox and Chrome, and if you want a paid subscription, it's only $10 per YEAR. I said screw it and gave them some money, they deserve it!
What else is really cool about Bitwarden is that I found it in Fedora's software center, all I had to do was click "Install". Needless to say I'm happy with it, and I recommend it for anyone looking for a password manager.