In Big Sur through many earlier releases, you can hold down the Option key and select > System Information and click the Power item under Hardware in the left-hand navigation bar. If the battery dies entirely, an X appears through the battery icon, and the message reads No Battery Available. You may also see one of a number of other messages that Apple doesn’t document, such as Service Recommended, Replace Soon, or Replace Now, all of which have a little more urgency, as the operating system has deemed the battery holds a charge poorly, or even not at all. The condition should be listed as Normal, but if the battery’s maximum capacity has dropped below a certain point (which Apple doesn’t specify), it might say Service Battery.
Big Sur shows the current battery parameters, but not battery health.