As for the 3D thing: you are allowed to publish anything that belongs to you and is created by you (as long as the contents don't break the site rules). Your content can also contain, but not entirely consist of, things for which you purchased the license to use, and royalty free assets. As long as the original creator of those assets have allowed people to use them for commercial use, of course.
As for nsfw content, i would suggest you make the comic the way you want first, adjust it for tapas and webtoon later. You can upload the uncensored version to patreon or somewhere else. If on patreon, make sure only patrons can see it or patreon might shut your account down.
For tapas you need to censor, and add a mature content tag to anything containing:
- erect genitalia and lubricated genitalia. Also otherwise sexually displayed genitalia.
- genetalia being penetrated by any bodypart or object, genitalia being licked or otherwise handled orally.
- anal penetration, anal licking
- genitalia being carressed sexually
The following does not require censoring but requires a mature content tag still:
- nudity in a sexual scenario, butts primarily
- non sexually displayed genitalia (for example if you have a non sexual scene that takes place on a nudist beach or in a dressing room. Or maybe your story takes place in a universe that has a different approach to clothing!)
- petting on outside of clothes
The following does not require a mature content tag:
- upper body nudity. As far as I understand, Tapas does not treat lady nipples differently than guy's nipples.
- if your characters kiss and hug and have a slightly suggestive convo before the deed, that part ofc doesn't need to be hidden. Anything heavily suggestive may be best off behind a mature content tag.
As for webtoon... any page that has the sex scene in it, don't post it there. Be careful with nudity overall. I got a page removed for nudity once, even though no genitalia was on it. The dick was just out of sight and the man in question was in a bathtub washing blood off from a fight.