Printable View
To everyone who still has this question or looks this up:
Hold L1 + R3 to bring up virtual mouse, then "click" the text box with R2 and choose the size, all the way up to 200%.
Someone mentioned it didn't work in an earlier 2017 post, but it is proven functional now in 2019 and has been since at least 2018.
Like Rothare above said, using the virtual mouse resizes the window. HOWEVER, it must be a chat bubble in the open world, not a cutscene. Right clicking the bubble in a cutscene just advances the text. You have to be conversing to the NPC in the open world for it so work. This is true as of 2022