I gained a size from weight training

I was wondering if I should keep to the weight training or change my journey to more cardio?

That really depends on your goals/wishes…me personally switch between weight training and more cardio. But that is due to very fast muscle gain on my site…
So, think about what you are chaising for: all day strength, endurance, a certain look or mental well beeing and second choose the journey helping you to get there