Hello,
Just to add my usecase to the discussion. I use evernote extensively for pro and personal purposes (and I've been a premium subscriber for years). In my personal life, I write novels. Some of my books contains +80 chapters. I tried to use Evernote many times to outline my books but it's quite impossible to manage without an expand/collapse feature and I'm forced to use another tool (ie Notion) just for this part of my digital life. It would be a very cool moove from evernote to add this feature to the product.