what's the default scheme in xcodebuild?

When I run xcodebuild -list, I will get

Targets:
    iKM
    iKMTests
    dailybuildipa

Build Configurations:
    Debug
    Release
    DailyBuild

If no build configuration is specified and -scheme is not passed then "Release" is used.

Schemes:
    dailybuildipa
    DemoApp
    Documentation

but in practice ,I did not set specific scheme in my build command(because i did not use workspace for building)

 xcodebuild -target dailybuildipa -configuration DailyBuild -sdk iphoneos12.2

so in this situation, which scheme the xcodebuild will use as default scheme?

or it's because xcodebuild can build without any scheme?