public interface IServiceScopeFactory<T> where T : class
{
    IServiceScope<T> CreateScope();
}

public interface IServiceScope<T> : IDisposable where T : class
{
    T Service { get; }
}

public class ServiceScopeFactory<T> : IServiceScopeFactory<T> where T:class
{
    private readonly IServiceScopeFactory _serviceScopeFactory;

    public ServiceScopeFactory(IServiceScopeFactory serviceScopeFactory)
    {
        _serviceScopeFactory = serviceScopeFactory;
    }

    public IServiceScope<T> CreateScope()
    {
        return new ServiceScope<T>(_serviceScopeFactory.CreateScope());
    }
}

public class ServiceScope<T> : IServiceScope<T> where T : class
{
    private readonly IServiceScope _scope;
    private T _service;

    public ServiceScope(IServiceScope scope)
    {
        _scope = scope;
    }

    public void Dispose()
    {
        _scope?.Dispose();
    }

    public T Service => _service ?? (_service = _scope.ServiceProvider.GetRequiredService<T>());
}

public class Foo
{
    private readonly IServiceScopeFactory<ConmaniaDbContext> _dbContextFactory;

    public Foo(IServiceScopeFactory<ConmaniaDbContext> dbContextFactory)
    {
        _dbContextFactory = dbContextFactory;
    }

    public void Bar()
    {
        using (var scope = _dbContextFactory.CreateScope())
        {
            var dbContext = scope.Service
            //use service
        }
    }
}

public static void AddServiceScopeFactory<T>(this IServiceCollection serviceCollection) where T : class
{
    serviceCollection.AddTransient<IServiceScopeFactory<T>, ServiceScopeFactory<T>>();
}

services.AddScoped<ConmaniaDbContext, ConmaniaDbContext>(); //Scoped Service
services.AddServiceScopeFactory<ConmaniaDbContext>();
services.AddSingleton<Foo, Foo>(); //Singleton Service

public class Foo
{
    private readonly IServiceScopeFactory _scopeFactory;

    public Foo(IServiceScopeFactory scopeFactory)
    {
        _scopeFactory = scopeFactory;
    }

    public void Bar()
    {
        using (var scope = _scopeFactory.CreateScope())
        {
            var dbContext = scope.ServiceProvider.GetRequiredService<ConmaniaDbContext>()
            //use service
        }
    }
}