>>1965145>>1965148it's not 100% necessary, but it gives you more options (at least in tso2pmd, i haven't managed to run succesfully tso2pmx, maybe in that one you need the game): as long as the saves don't use mods, tso2pmd will load it without need of 3dcg installed on your pc.
you can also get only the mods, which can contain hair, clothes, body sets, that kind of stuff, and then mess with their proportions in the last tab of the program, export them separately and then combine them all in pmxeditor. sure, it's more complicated but it lets you manipulate the model more and gives you more results.
these mods usually are tso files (hence the "tso" in tso2pmd and tso2pmx), in others they are packed together as another file called tah files, which you will need to decrypt via a program (tahdecrypter, i think i posted a link like half a year ago after searching for it, or someone else did it).
having the game and its mods will improve your custom options though: you could create your own proportion files and put them in the proportion folder of tso2pmd/pmx, i think you can also create your own morphs (which are saved as tmo files) which you can put in the morphs folder too; using the default morphs on different body sets would probably make not so great results, especially if you mess the face's proportions
this pic shows the tso file of a mod loaded into tso2pmd, and i was playing with the tits' propportions via a cs file (the proportion files come in these things). in this case, it's a mix of the default proportion files the program come with and others that came from an anon's collection.
the pastepin in the op has a link for a bunch of things related to 3dcg, and also the collection of cs files of that anon and a link to the jap's mod database, and an outdated list that tells what does each mod have