this is a component from Devart, so either contact them or modify the sources yourself, just remember that with each update will have to do it again.
I don't know what it looks like for MyDAC, but in SDAC there is a Sources\Design directory that contains the DASQLFrame pas and lfm files, and you either open in Lazarus and use ObjectInspector to increase the font for TMemo, or in Notepad you edit the lfm file and set the font size there.
Then you need to recompile the component.