I've found many scenes in The Witcher 3 to be very pretty and I'd like to record them by taking a screenshot.

Is it possible to take a screenshot actually in-game? If it is, how is it done?

I am playing the game on PC using the GOG Galaxy Beta client.

Referring to this thread, it seems that the only way is a third party solution, such as Fraps or 'Non-Steam game' link and overlay, but are they correct in assuming the game has no built-in screenshot functionality?