As per my understanding you wanted the markers in different sizes and want those to be labeled in the legend with the size being shown .You can achieve this by refering to the below code -
x = 1:3;
y1 = x.^2;
y2 = x.^3;
% Define marker sizes for each point
ms1 = [4, 6, 8];
sizes = [50,300,650];
% Plot the data with different marker sizes
figure;
for size = 1:3
hold on;
plot(x(size), y1(size), 'o', 'MarkerSize', ms1(size));
hold off;
end
%write the legend corresponding values
x = cellstr(num2str(sizes', '%-d'));
% Add a legend with marker sizes
legend(x);
