Using appsettings.json in .Net 6 Worker service

Question

Is I wanted to add a singleton service that is dependent on appsettings.

How would I do this in the .Net 6 worker service startup?

using AutoMapper;

var mapperConfig = new MapperConfiguration(mc =>
{
    mc.AddProfile(new MappingProfile());
});

IMapper mapper = mapperConfig.CreateMapper();

IHost host = Host.CreateDefaultBuilder(args)
    .ConfigureServices(services =>
    {
        services.AddHostedService<Worker>();
        services.AddSingleton(mapper);
        services.AddSingleton<IOrderNumberGenerator, OrderNumberGenerator>();

        services.AddSingleton(new ServiceIwantToCall(<--I need too use apsettings here-->));
    })
    .Build();

await host.RunAsync();