Raspberry Pi WiFi Range Extender: Ways to Extend or Share a Network

It can be configured for access-point or hotspot use, but a true repeater arrangement depends on compatible wireless hardware and network configuration. Raspberry Pi's official guide describes hotspot setup; it is not a universal one-click extender mode.

It may be used in a custom networking setup, but check the current Raspberry Pi documentation and the exact wireless interface for supported modes before planning it as a repeater.

A Raspberry Pi 3 can be part of a DIY access-point project where its hardware and configuration support the required mode. The result takes setup and should not be assumed to behave like a plug-in booster.

Not by itself. The Pi hotspot broadcasts a wireless network; to provide internet, the Pi also needs an upstream connection, such as Ethernet or a separately supported wireless connection.

That depends on whether you want a configurable project or a simple coverage device. A Pi requires setup and maintenance; a dedicated extender is designed for a more straightforward home installation.