Graphical inequalities aren’t quite how you’d want them to be on Desmos, simply because it shades the side of the line that produces true statements rather than false. Of course, in linear programming with multiple inequalities, you really want the true sides left blank for clarity. So you have to cheat and reverse your inequality signs to get Desmos to shade the way you want it to, but it’s still a lovely visual.
I’ve made up an example, and shown how you can use a slider to get the objective line to move within the region. Since you can click on points of intersection, it’s easy to consider all the vertices of the region as well.