Thank you very much for choosing our theme and for contacting us.
You can resize the icons if they are SVG.You need to open your SVG icons file with some editor like Sublime Text or default system text editor and add width=”31″ height=”40″ attributes to your <svg> tag like it is shown: http://prntscr.com/m4n0qw
Then you will need to re-upload your icons in WordPress Dashboard.
If they are png/jpg you can increase them only in the image editor.