With the release of MSBuild version 15, you no longer need to add custom properties to every project in your solution. Instead you can create a single file called Directory.Build.props in the root folder of your source.When MSBuild runs, it will search for this file and loads it when found.
I use this on my projects to set common properties:
Directory.Build.props is imported very early in the build pipeline and can be overridden elsewhere in the project file or in imported files. If you want to override properties set in a specific project, use Directory.Build.targets instead. It is used and discovered in the same way, but it is loaded much later in the build pipeline. So, it can override properties and targets defined in specific projects.
More information: https://docs.microsoft.com/nl-nl/visualstudio/msbuild/customize-your-build?view=vs-2019#directorybuildprops-and-directorybuildtargets