// @nuget: Microsoft.EntityFrameworkCore.Sqlite -Version 8.0.8

using System;
using System.Data;
using System.Linq;
using Microsoft.EntityFrameworkCore;

using var db = new BloggingContext();

var query = (from blogs in db.Blogs
	select (from posts in blogs.Posts select posts).OrderBy(e => e.SortKey).Take(1).OrderBy(e => e.Id).Single().Id);

Console.WriteLine(query.ToQueryString());

public class BloggingContext : DbContext
{
    public DbSet<Blog> Blogs { get; set; }
    public DbSet<Post> Posts { get; set; }

    protected override void OnConfiguring(DbContextOptionsBuilder options)
        => options
            .LogTo(Console.WriteLine, Microsoft.Extensions.Logging.LogLevel.Information)
            .UseSqlite($"Data Source=test.db");
}

public class Blog
{
    public int Id { get; set; }
    public Post[] Posts { get; set; }
}

public class Post
{
    public int Id { get; set; }
    public Blog Blog { get; set; }
    public int SortKey { get; set; }
}