How to specify the index option, fe FILLFACTOR?

CREATE NONCLUSTERED INDEX [IX_Name] ON [dbo].[Demo]
(
	[Name] ASC
)
WITH (FILLFACTOR = 80) ON [PRIMARY]

modelBuilder.Entity<Demo>(entity =>
{
      entity.HasKey(e => e.Gid);
      entity.HasIndex(e => e.Name).HasName("IX_Name");
});