For ervery loop, you have only one point (x,y) which you can not plot as a line. Use plot(x, y, 'bo') to plot the point instead. If you want to join the dots, you need to store the (x,y) values over the loop.
clear all;clc;
syms theta v omega omega1
% Given
mu0=3.63*10^(-7);
T=30;
T0=518.7;
s=198.72;
while T<110
mu1 = mu0*(((T+459.67)/T0)^(1.5)) * ((T0+s)/((T+459.67)+s));
T=T+10;
fprintf("%e\n",mu1);
x=T;
y=mu1;
hold on
plot(x,y, 'bo');
end
fprintf("More collisions in a gas means more momentum transfer making the gas more viscous.",mu1);
hold off
