I am shopping for my first Marklin HO train. I would like the full selection of DCC features to be available, sounds, lights, smoke. I will operate it with the Roco/Fleischmann z21 system. So, for example, I'm looking at the 39209 Class 1.5 loco. It is an Era IV steam loco with the look and features I want. I can pull Era IV cars like the Slberlinge or POP cars. And it runs the more impressive 7226 smoke unit. The specs say it has mfx+ and DCC decoder. The features chart shows very limited features for "Control Unit" and "Mobile Station" and even for "Mobile Station 2" and "Central Station 1/2" it isn't until the "Central Station 3/2" column that all features, including some I really want like station announcements, become available. But i will not be using a Marklin controller.
Please feel free to make other suggestions as well, as I have a lot to learn I don't want to be overly specific about this part numbered loco. My only requirement for the cars is that they be prototypical for the loco and have interior lighting.
I guess Era isn't so important, looking at Marklin 26928 1928 Rheingold Train Set it is Era II but i still have the same questions about features operation.

Yes but can these functions or how many of these functions be operated with a Roco z21? Is a Marklin controller required for some of these functions?

The Z21 can control up to 29 functions (F0 and F1-F28), and Z21 does not support Mfx.
Would also recommend that you lock closer into the cs3, before you buy. With CS3 you can control locomotives wireless trough a browser using any device/tablet, or apps on your phone. Ore you can use VNC viewer.
(marklin/LGB has also de dedicated wireless radio controller)

No, Z21 does not support more than 29 DCC functions, ref Z21 FAQ page.

It sounds as if the z21 can be used with Marklin HO features. And the z21 and Z21 both support the same number of DCC functions. I thought it was odd that, for instance, the features chart of a Minitrix N loco has a column for DCC, and all of the available functions are checked off there, but the Marklin HO chart does not have a column for DCC, just the columns I listed in the original post. It just says DCC in the product description. So I wanted to know if there was something limited about DCC ops. Anyway, it doesn't sound like there is. I'm goin to do a search and maybe start another thread about Roco/Marklin ops but I think I can buy a HO Marklin and operate it with a z21! Much appreciated.

Hi!
Era IV was the time of the iron curtain.
There may be prototype photos for a BR 01.5 with Popwagen, but I think it's unlikely to have it with Silberlinge. But I didn't check prototype photos and maybe both variations have happened in history.
Märklin offered a nice set of Tillig coaches for this loco, but IIRC installing interior lights is a bit difficult.

Good point, that is a backup plan, CS2.
So I ordered Marklin 26928 1928 Year of the Rheingold set. Era II. No concerns about prototypical train with that set! Should look beautiful!

Oh! Cringe. I guess Marklin takes some liberties too, but we know that. Yesterday I found three pages of forum discussing this set, coming from Z scale I was floored by that! From the Wikipedia link there I read about the alternating kitchen coaches (which I cannot reproduce) and additional baggage car. Some on the forum thread were adding a Brawa baggage car which I would do but I could not find one. There were no pictures of the train on Wiki. But it is a great train, isn't it? At least I'll have a colorful story to tell visitors as this train will run in a prominent place in my home ;)