You can open the saved figure with the openfig function.
f = openfig('figure1.fig');
You can modify any property of the figure or anything in the figure. But you have to know how to find the object(s) you want to modify. findall can be used for that.
For example, modify the colors and sizes of the x/yticklabels of the axes:
f = openfig('figure1.fig');
ax = findall(f,'Type','axes')
ax.XColor = [0 1 1]; % cyan
ax.YColor = [1 0 1]; % magenta
ax.FontSize = 16; % font size of all tick labels
The axes x/ylabels and titles are text objects, so you can use findall to find all text objects in the figure, then modify their properties:
t = findall(f,'Type','text')
t(1).Color = [1 0 0]; % make title red
t(2).Color = [0 1 0]; % make xlabel green
t(3).Color = [0 0 1]; % make ylabel blue
set(t,'FontSize',16) % make all 3 into 16-point size
