UI elements too small

My wife and I have Android phones running the Roon app. On mine the GUI displays fine but on my wife’s phone the letters are so small that they’re barely readable. This happens only with the Roon app, all other app GUIs display well. Her phone is a Wiko Pulp 4G, it has a resolution of 720x1280 and runs Android 5.1.
Is there something that can be done about this?

I agree.
Samsung Galaxy S7, the UI interface elements (i mean… the text elements) are so small that it’s almost impossible to select/press them.