I do have some large-capacity external drives. I wish there were a way to have everything saved there in real time. Maybe there is but I’m just not aware of it.
That would the PC; not the cell phone.
Apple makes good software called “Time Machine” to do that, but that doesn’t help you. I tried using Time Machine with an external drive connected to our router/wifi access point, but had mediocre results. I just asked Grok “how can I make background backups on a PC to an external hard drive attached to my router?” and it came back with a complete set of directions on how to do it. It’s not terribly hard.
I use cloud backup to Apple iCloud and it works very well. Very seamless and transparent. I can access any documents from any device. It’s come in very handy for accessing files when I’m away from home.