Hopefully this isn't too overwhelming, its not easy for me sometimes. But I thought I'd say enough to clear things up; if I did. I hope so at least.
I know the 1.13 or 1.13.2 version of Voxel Map is available. It requires Rift Modloader though not Liteloader this time. Rift supports 2 mods for 1.13.2 at least on Curseforge as thats the only site I use to track 1.13 mods as Rift is also housed on Curseforge and Curseforge is a safe site unlike the mod repost/dodgey sites saying 1.13. mods exist when they don't by their definition and Forge isn't a thing for 1.13 yet. And I document 1.13 & 1.13.2 mods as well as Rift so I try my best with the knowledge I have, and I try to make it accurate since I update a thread for it very very often.
1.13.2 modding with Rift is very new, hence why its not well known yet. I don't state server access though, so I can only talk about my singleplayer experiences but if you want to answer questions like that then ask those mod creators that support Rift and 1.13 or 1.13.2 environment to be sure if they are server accessible even with or without datapacks if likely.
If you mean server mods or bukkit I'm unable to help you, if you want a modded environment like Forge with map mods I can help you then, but its not using Forge, it just works like Forge in a way. Its called Rift.
You can try that here (they also have a link to the 1.13.2 version of Rift too since the main Rift page doesn't have it for whatever reason I don't know):
I have a tutorial as well as if you'd like to follow to help install it. I don't install optifine with it though but its not too hard if you extract optifine and put it in the mods folder, after setting up a Rift modloader installation.
My tutorial for Rift 1.13.2 i uploaded a few days ago:
I document the 1.13 & 1.13.2 modding community 'Rift Discussion Section' thread to state what is legit for players to use in 1.13 or 1.13.2 modded environments with mod lists, mod and datapack conflicts, tutorials to install the Rift modloader (NOT FORGE SINCE FORGE FOR 1.13 versions DOESN'T EXIST AS OF WHAT I KNOW RIGHT NOW, OR AT LEAST NOT FOR PLAYERS) into Vanilla, MultiMC5 & Twitch.
I only state Rift supported mods from the sources of Curseforge or Github right now as the safest and legit sources for mods (Github only if its a major mod and is by a recogniseable creator like I did and confirmed with the Aether Legacy creator for the Rift Edition alpha version of it).
There are also, because I can't take all the credit, youtubers that post videos on Rift tutorials and mods along with an install for the Rift modloader besides myself, but I myself update the thread and created the thread so...
But I update the Rift Discussion thread often once I see mods updated or come up with ideas of information to mention like the Rift & Datapacks conflict possibilities, or 1.13.2 mod lists or other things which I've added recently to that thread in new posts often.
When it comes to Realms, Realms is a Mojang owned thing and I don't know how Realms and Mods works, didn't know with 1.12.2, so you'd have to wait until some else can answer that for you if its possible for mods no matter the mod loader (Forge or Liteloader) to run with Realms.
I assume not since Mojang has nothing to do with mods and mods are a community thing, but I can't answer that properly if it is possible.
My link to that thread is here if you want to take a look. I don't force players, I just give them the information to avoid confusion with 1.13 Forge or 1.13 modding possibilities, mod lists and tutorials are available, and mod spotlights are also there, I try my best to help players out, I give the information they need and they can take it or leave it, its up to them: