Not for the icon in the grid, but I have found a way to resize the icon panel.
Line 21 in travelButton.lua, change self:SetSize(32, 32); to self:SetSize(48, 48);
Resize also the picture file travel.tga in ressource folder from 32x32 to 48x48
https://zupimages.net/viewer.php?id=22/36/ixra.png