You have to include the library at the root-level _Imports.razor file through the @using directive.
You can consume a library in either of two ways:
If the MyComponentLib is the component library and MyComponent is the component name, those are consumed like in the following.
<h1>Hello, world!</h1> Welcome to your new app. <MyComponentLib.MyComponent />
@using MyComponent <h1>Hello, world!</h1> Welcome to your new app. <MyComponent />
Refer to the link Consume Blazor a library component.Permalink
You have to use the following command to include a Blazor component library application.
dotnet new razorclasslib -o MyComponentLib1
Refer the below documentation link for more information.
Create a Razor class library for Blazor using .NET Core CLIPermalink
In Visual Studio 2019’s latest preview, create an ASP.NET Core web application and choose the Razor Class Library template with ASP.NET Core 3.0.
Refer to this Microsoft link for more information.Permalink