We always need more storage. Regardless of your device, you’ll likely need a bank of secondary storage to backup content or store primary copies. Considering these expanded storage needs are usually required on multiple devices, the easiest way to make this accessible is to use a network-attached storage solution.
You can buy network-attached storage units from popular manufacturers like Synology and TerraMaster or build one yourself. To do the latter, you’ll need hardware and software. The former could be a second-hand PC or even a Raspberry Pi. As for the software, you could install a Linux distro and do it yourself or use a network-attached storage solution like TrueNAS, OpenMediaVault, or Unraid.