Single Build with Multiple Artifacts
Here is my YAML for multiple artifacts from a single build.

pool:
  name: Hosted Windows 2019 with VS2019
  demands:
  - msbuild
  - visualstudio
  - vstest
  - npm

steps:
- task: NuGetToolInstaller@0
  displayName: 'Use NuGet 4.4.1'
  inputs:
    versionSpec: 4.4.1

- task: NuGetCommand@2
  displayName: 'NuGet restore'
  inputs:
    restoreSolution: '$(Parameters.solution)'

- task: VSBuild@1
  displayName: 'Build solution WebApi'
  inputs:
    solution: '$(Parameters.solution)'
    msbuildArgs: '/p:DeployOnBuild=true /p:WebPublishMethod=Package /p:PackageAsSingleFile=true /p:SkipInvalidConfigurations=true /p:PackageLocation="$(build.artifactstagingdirectory)\\"'
    platform: '$(BuildPlatform)'
    configuration: '$(BuildConfiguration)'
    msbuildArchitecture: x64

- task: PublishBuildArtifacts@1
  displayName: 'Publish Artifact: WebApi'
  inputs:
    PathtoPublish: '$(build.artifactstagingdirectory)'
    ArtifactName: 'dotnet-webapi'
  condition: succeededOrFailed()

- task: DeleteFiles@1
  displayName: 'Delete build.artifactstagingdirectory for Angular'
  inputs:
    SourceFolder: '$(build.artifactstagingdirectory)'
    Contents: '**'

- task: Npm@1
  displayName: 'npm install'
  inputs:
    workingDir: project/ClientApp
    verbose: false

- task: Npm@1
  displayName: 'npm run prod-build'
  inputs:
    command: custom
    workingDir: project/ClientApp
    verbose: false
    customCommand: 'run prod-build'

- task: Npm@1
  displayName: 'npm run dev-build'
  inputs:
    command: custom
    workingDir: project/ClientApp
    verbose: false
    customCommand: 'run prod-dev'
  enabled: false

- task: CopyFiles@2
  displayName: 'Copy Angular/Dist to build.artifactstagingdirectory'
  inputs:
    SourceFolder: project/ClientApp/dist/ClientApp
    Contents: |
     **
     !config.json
    TargetFolder: '$(build.artifactstagingdirectory)'

- task: PublishBuildArtifacts@1
  displayName: 'Publish Artifact: Angular'
  inputs:
    ArtifactName: angular