There are actually a few different ways you can check your Core Web Vitals and there's actually two kinds of scores you can look. The first one is lab scores and the other you can think of as live scores but they call it field data. These are your live scores meaning scores that you're accumulating by users accessing your site and transmitting their scores to Google's own database for their ability to measure these things.
Lab scores are scores you can look at in your web browser using Dev tools. There's a Lighthouse tab in Dev tools, there is a chrome plug-in for getting Lighthouse pulled into your browser too. You can also go to PageSpeed Insights. They have Core Web Vitals at the top and they have a bunch of feedback and information.
If your site is popular enough to have enough statistics play into the field data database they have over a big query they call the crux report data. If it's big enough for that then you'll see both field data and lab data so look for that if you working on behalf of a popular site.
If it's not so popular you're only seeing that lab data don't fret it's actually still pretty pretty solid information of note. Field data tends to be a little worse than your lab data because most of us are doing these scores in the lab using a computer with an advanced chip and high speed access to the network and that's not always the case for people accessing your website. Some might be on a slow network using an underpowered laptop or some may be on a mobile phone or some other kind of underpowered device so that the actual average scores you're getting from the field tends to be worse than you what you get in the in the lab.
You want to optimize and get hundreds across the board. If you get 100's in lab then you shouldn't see failing scores in your field data unless there's some kind of anomaly which we would need to debug and figure out. Your field data is the more reliable one as a correlation to your ranking factor in these Core Web Vitals but lab data is better for your debugging troubleshooting and improving your website.