I really love the format that DnD beyond has for creating characters and putting in their backstories. I have even used it for character that I'm writing in a book and wont use for dnd. But I am now running into the problem of having a bunch of characters to scroll through to find the one I'm looking for.

Is there a way to put characters into a folder of some kind under collections>my characters ?

This would help me the most with sorting into old campaigns, characters from my book, NPC's that can work in any world, and NPC's that are specific to my current campaign. I have added NPC in front of their name too, but there's still a lot.

As weird as it sounds, it is probably easier to manage your characters using My Campaigns rather than My Characters. Just name a group of campaigns along something like "ZZZ — [Character Folder Name]" or "000 — [Character Folder Name]". If you want your actual campaigns to appear on top, then put ZZZ in front of your character "folder" campaigns. If you want your character "folders" to appear on top, then put 000 in front of your character "folders".

So for example, you can create campaigns called "ZZZ — UA Master Copy Templates", "ZZZ — Public Sharing", "ZZZ — NPCs", "ZZZ — Characters, Ideas", "ZZZ — Characters, Ready to Use", "ZZZ — Characters, Retired", and so on and so forth.

Character folders is an oft requested feature, but until Beyond implements them, My Campaigns is probably the best workaround we have right now.