var
  h: TNetHTTPClient;
  r: TNetHTTPRequest;
begin
  h := TNetHTTPClient.Create(nil);
  r := TNetHTTPRequest.Create(nil);
  h.UserAgent := 'Mozilla/5.0 (Windows NT 6.1; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/64.0.3282.186 Safari/537.36';
  r.Client := h;
  r.Accept := 'text/html,application/xhtml+xml,application/xml;q=0.9,image/webp,image/apng,*/*;q=0.8';
  r.AcceptEncoding := 'gzip, deflate, br';
  r.AcceptLanguage := 'ru-RU,ru;q=0.9,en-US;q=0.8,en;q=0.7';
  r.URL := 'https://СайтНаHTTP2.com';
  r.MethodString := 'GET';
  Memo1.Text := r.Execute().ContentAsString();
end;

program Project1;

{$APPTYPE CONSOLE}

uses
  System.Classes, IdHTTP, IdSSL, IdSSLOpenSSL, IdSSLOpenSSLHeaders, IdCTypes;

type
  TCustomIdHTTP = class(TIdHTTP)
  public
    constructor Create(AOwner: TComponent);
  private
    procedure OnStatusInfoEx(ASender: TObject; const AsslSocket: PSSL; const AWhere, Aret: TIdC_INT; const AType, AMsg: String);
  end;

{ TCustomIdHTTP }

constructor TCustomIdHTTP.Create(AOwner: TComponent);
begin
  IOHandler := TIdSSLIOHandlerSocketOpenSSL.Create(nil);
  with IOHandler as TIdSSLIOHandlerSocketOpenSSL do begin
    OnStatusInfoEx := Self.OnStatusInfoEx;
    SSLOptions.Method := sslvSSLv23;
    SSLOptions.SSLVersions := [sslvTLSv1_2, sslvTLSv1_1, sslvTLSv1];
  end;
  inherited Create(AOwner);
end;

procedure TCustomIdHTTP.OnStatusInfoEx(ASender: TObject; const AsslSocket: PSSL; const AWhere, Aret: TIdC_INT;
  const AType, AMsg: String);
begin
  SSL_set_tlsext_host_name(AsslSocket, Request.Host);
end;
//////////////////

var
  MyHTTP: TCustomIdHTTP;
begin
  MyHTTP := TCustomIdHTTP.Create(nil);
  Memo1.text := MyHTTP.Get('https://СайтНаHTTP2.com')
  MyHTTP.Free;
end.

  IdSSL := TIdSSLIOHandlerSocketOpenSSL.Create;
  IdSSL.SSLOptions.Method := sslvTLSv1_2;
  IdHTTP.IOHandler := IdSSL;