How to upgrade to macOS High Sierra (10.13) - Apple Support (if you're not already on High Sierra) How to upgrade to macOS Mojave (10.14) - Apple Support
How to upgrade to macOS Catalina (10.15) - Apple Support Other app updates can have different requirements. If you want those or other app updates, or if you want or need an app that requires a macOS version newer than High Sierra, then you will need to upgrade macOS-an upgrade to a new macOS version such as to High Sierra or Mojave, as differentiated from an incremental update to a later version of High Sierra, though you're probably already at the final version of High Sierra-if your Mac is supported by those newer macOS versions. In Apple macOS usage, upgrades are larger and can be more disruptive and can provide new features, where updates largely provide minor changes and fixes.
You can choose to ignore those updates, as will macOS itself.
Those incompatible app updates are because those apps require later versions of macOS.
