So just for fun I thought I'd try running LOTRO using DirectX 11.
If you have time on your hands and read my entire thread about Crossover and Big Sur here...
https://www.lotro.com/forums/showthr...Big-Sur-11-0-1
...then you know that LOTRO runs great with Crossover and Big Sur.
Once the game is installed and you've gotten it to run successfully at least one time, you can enable DirectX 10 if you want to. If your choice is between DirectX 9 and DirectX 10, I suggest you stick with DirectX 9. DirectX 9 has a few minor graphics glitches mostly related to drawing distant target circles, nearby AoE squares (such as a Lore Master's tar patches), and some shadows and lighting effects get cut off in odd ways when moving through some areas. It's not a big deal in any way, you get used to it and none of it breaks immersion. DirectX 10 doesn't have those issues but it has really major ugly glitches in certain areas that cause landscape objects to flicker between their normal appearance and bright white (in Rivendell and the Shire and, to a lesser extent, Evendim based on my testing so far), and it doesn't handle water very well causing some river beds such as in Evendim to appear less full of water than they should or completely empty depending on the position and angle at which they are being observed plus things like the mist at the Rivendell waterfalls at the bridges just aren't handled well at all. DirectX 10 is a better choice when not in one of the areas where those glitches happen, but you can't switch between DirectX 9 and DirectX 10 without quitting and restarting the game so it's really better to just stick with DirectX 9. Things look beautiful with DirectX 9, I have no major complaints with it.
Even so, I thought I'd try DirectX 11. LOTRO has it available, it's just a matter of getting Crossover set up so that LOTRO will detect that DirectX 11 is an available graphics mode for it to use. And getting Crossover set up for DirectX 11 is trivial.
1- Launch Crossover.
2- In the list of "bottles" in the Crossover window, look for the bottle into which you have installed LOTRO. Right-click on that bottle name.
3- Look for SETTINGS, hover over that, then look for DXVK BACKEND FOR D3D11 and choose that.
3a- If you don't have an option to enable DXVK BACKEND FOR D3D11 then you need to install "DirectX for Modern Games" into your bottle first. Also note that your bottle must be a 64-bit bottle in order to use DirectX 11; you should have set it up that way anyway since you can't run the 64-bit LOTRO client unless the bottle is 64-bit.
edit 2021-02-13: My current best advice is to install "DirectX for Modern Games" even if you can enable DXVK BACKEND FOR D3D11 without it. "DirectX for Modern Games" installs additional and updated components which will improve the graphics performance and stability of LOTRO within Crossover regardless of your choice of primary graphics driver (DirectX 9 or DirectX 11).
That's all there is to it. On next launch of the LOTRO launcher app it will detect that DirectX 11 is available and will ask if you want to use it instead of whatever you were using (DirectX 9 most likely, but possibly DirectX 10). Just say YES and when you get into the LOTRO client you will be using DirectX 11. Note that DirectX 11 requires more "horsepower" than DirectX 9 or DirectX 10 so your framerates might be lower – they were not for me, I have mine capped at 30fps anyway. You can then go into the advanced graphics options and turn on even more eye candy.
The best part about DirectX 11 is that it doesn't have any of the glitches I've noted with either DirectX 9 or DirectX 10: No issues with distant target circles or nearby shadowy things such as Lore Master tar patches, no issues with tree flickering or disappearing river water, no issues with mist at waterfalls... no problems at all so far everywhere I've tested. And things look really nice. Things look really nice with DirectX 9, too, but they are a just that tetch better with DirectX 11.
Remember that the "Mac"/WINE client provided for us Mac users by SSG which runs only in versions of MacOS which are Mojave or earlier will run only DirectX 9. And that's fine, DirectX 9 works great and the minor graphic glitches are not a big deal and you might not even notice them much. But if you're running the normal Windows client installed into Crossover, do try DirectX 11 because it has none of the problems of DirectX 9 or DirectX 10 and looks amazing at the cost of only a little bit of framerate.
edit: 2021-03-18: Most people report the same or better framerates with DirectX 11 vs DirectX 9.
edit: 2021-03-19: Some people with Apple Silicon/M1 Macs and Intel Macs with Intel Iris Pro integrated graphics have reported failures to successfully run the LOTRO client with DirectX 11 even though they enjoy perfectly functional gameplay with DirectX 9. If you have a Mac with an Apple Silicon/M1 processor or Intel Iris Pro integrated graphics, it won't hurt anything to try DirectX 11 but you need to go into it as an experiment that might not work for your specific hardware.