I’m using right now, and I already enabled this feature in Google Translate.
When copy text, a bubble of Google Translate should appear on the screen. One more thing that I noticed is on my another Samsung phone, I even get more menu depends on the app that I installed when copy text, for example Translator app from Microsoft, but none of these menus appears on my Pro 5.

This is a picture of menu on my Samsung phone.

Does anyone has this problem?