Question: how can i get maximize in dsolve numeric

hi . i want to get maximize in dsolve numeric y(t) D(y)(t) and y(t) double dot

restart;
with(plots);
with(Optimization);
sol := {diff(y(t), t, t) + 2*diff(y(t), t) + 4*y(t) = 0.9*sin(9*t), y(0) = 0, D(y)(0) = 0};
so := dsolve(sol, numeric, method = rkf45);
plots:-odeplot(so, [t, y(t)], t = 0 .. 4);
Maximize(??????);
 

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