Hi all. I'm coming back to this thread because I'm still struggling with my inbox

I have two questions:
1) is there a possibility to increase your inbox? I know I never have enough

2) if we really can't increase, and I have to download old messages, is there a way then to upload the document here, like we do with photos albums? So we would keep them here. It would feel safer for me, personally, and it would feel less like deleting them from PC.
It's just that I hate the idea of deleting my messages
Thank you and sorry if I insist on this topic.