Just follow these steps and you're done without using any 3rd party softwares! (Cool)
1. Run TurboC++, right click on top of the console window and click properties.
2. Under properties, select the font tab. Follow the settings as shown on the image below,the bigger the font size the better the window size.
3. Don't forget to select "Lucida Console" as your font. I choose a fontsize of 28 so as if I maximize the window it will fit perfectly according to my screen size.
4. Click ok and you're done!