No, Focusrite makes audio interfaces (hardware) that you plug your guitar or mic or into so you can convert analog to digital and record it in your DAW. The interface plugs into your computer and uses a computer setting called "ASIO."

You need one if you are going to properly record guitars, vocals, bass and such.

Focusrite offers some free VSTs for mixing and EQing and such, but soft synths are a different world. They are virtual synthesizers that employ either midi or samples (or both) to create digital music, largely for keyboards, strings, pads, drums, on and on.

You should google soft synth and study it. It is a huge world man.