My name is Alex Mars, I am composer and sound designer at AK Audio and a tutor at XSSR Academy online music school.
There are many ways to create sci-fi texture sounds. You will need to know how to use synthesizers as well as know how and lots of inspiration.
A sound of future weapon should consist of several layers:
You can synthesize each layer separately. Some textures are created when you manipulate effects chain. Listen to how interesting these sounds can be.
Let me show you how I do my sound design: