The fontsize is relatively straightforward:
ax = gca;
ax.FontSize = 24;
will change the fontsize of the title, legend, and both x and y axes. If you want more customizability, you can change each individually by using the title, legend, xlabel, and ylabel commands with the FontSize option.
The linewidth should be adjusted by changing the default linewidth with the set function:
This will change the linewidth you see in your figure. There are most likely some other good ways to do this, but these are some of the faster ways that I like to use in my figures.
Hope that helps,