One way to do this is to use the following syntax: nexttile(tilelocation,span)
Below, I create a 2x4 grid instead of 2x2. Then I can place the axes as needed to get the desired appearance. Here, the first plot is placed in the first row, and spans the first 2 columns. The second plot is placed in the first row, and spans the next 2 columns (3&4). The final plot is placed in location 6 (2nd row, 2nd spot) and also spans 2 columns (6&7).
syms x y
figure
tiledlayout(2,4);
nexttile([1,2])
y = x^1;
fplot(x,y)
nexttile([1,2])
y = x^2;
fplot(x,y)
nexttile(6,[1,2])
y = x^3;
fplot(x,y)
