One of the biggest features Android 10 introduced is the system-wide dark theme. But some apps like Google Play Store, will enable and disable the dark mode depending on the system's settings. Well you'll soon get a toggle that will give you finer control over that.
According to recent reports from users running Android 10, the Google Play Store app now has an additional option in the Settings menu called "Theme". It allows you to force light mode when the system's settings is set to dark and vice versa. Or you can leave it to follow the system's default setting.
For now, the feature appears to be available only to select devices and there's no APK available for you to test it out. It's server-side, so you can only wait for now.