Which configuration for Office?

I'm looking for a laptop for my girlfriend right now.

For the model, I've actually already decided on the Yoga Slim 7.

Your only requirement is that nothing should hack. The laptop is only used for office, surfing and streaming.

But I haven't really found anything on such light loads in reviews.

Are the R5 4500U and 8Gb Ram enough for everything to run smoothly for several years or is the R7 4800U with 16GB variant more recommendable?

R5 4500U and 8Gb should be enough, since the laptop is not really used.