Using a smartphone as a laptop?
In which context?
No of course not. Those are two different things. You can't use a ship as your car either.
It works
In what way? Depending on the device, you could connect a normal Bluetooth keyboard to the cell phone and thus make typing easier.
But otherwise there are two pairs of shoes
In principle, it works. You can stream the cell phone display to a monitor via Smartview, pair it with a Bluetooth keyboard and mouse, or connect wired input devices with an OTG adapter.
Whether that makes sense is another matter, because the display is quite economical and small and does not expand on the monitor. It makes more sense to do that with a tablet. Since I write a lot myself, I regularly use my iPad as a laptop, but without an additional monitor.