Unfortunately, there is nothing you can really do. The Radeon R5 M335 dedicated GPU is actually not that much more powerful than the Intel HD 520. While there are a handful of laptops that do allow you to upgrade the dedicated GPU, these specific laptops are $1,400+ gaming laptops and replacement mobile GPU cards (MXM form factor) are typically at least $300+ and those are the lower end ones that are sold on ebay.
About the only thing you can do is to make sure there is no bloatware on your laptop and to play games that are not very demanding... which is the vast majority of modern games. You likely have to look at older games if you want decent performance.
About the only thing I can recommend is that you save up money for a laptop...