Linq Many to many in Entity Framework core

I have classes for building many to many relationships.

public class Chat 
{
    [Key]
    public Guid Id { get; set; }
    public ICollection<ApplicationUserChat> UserChats { get; set; }
}
public class ApplicationUserChat

{

[Required]

public string UserId { get; set; }

public ApplicationUser User { get; set; }
public Guid ChatId { get; set; }
public Chat Chat { get; set; }

}
public class ApplicationUser : IdentityUser

{

public ICollection<ApplicationUserChat> UserChats { get; set; }

}

For example, I have a user1 and user2

1. I need to Select chats for user1 where chat contains a user2
2. I need to select chat for user1 where chat contains a user2 and not contains another users (like one chat contains only 2 participants)
3. How I can do this in EF Core?

#c-sharp #entity-framework #.net #linq