Because of cost reduction, the model VivoBook you have has built-in 32GB eMMC as primary storage. This type of storage is soldered on the motherboard, it will be nearly impossible to replace/upgrade. It most likely will not be worth the time and money. While I can find models with 500GB or 1TB hard disk, I doubt the model you have has an option to add an extra hard disk.
In my opinion your best bet would be to sell this laptop and look for another one which has at least 128GB of storage, preferably with standard 2.5 inch drive/SSD or M.2 SSD. These are easily upgradeable when needed.