If class_1 doesn't have any handles inside, you can simply do:
x(100, 1) = Class_1(args);
for k = 1:100
x(k).prop1 = prop1(k);
...
end
You lose many benefits of preallocation if you reconstruct a new class every loop, but you could also use
x(100, 1) = Class_1(args);
for k = 1:100
cur_args = function_of(k);
x(k) = Class_1(cur_args);
end
Make sure you read https://www.mathworks.com/help/matlab/matlab_oop/initializing-arrays-of-handle-objects.html
"
A(4,5) = InitHandleArray;
results in two calls to the class constructor. The first creates the object for array element A(4,5). The second creates a default object that MATLAB copies to all remaining empty array elements."
So, if Class_1 has a handle object inside (like a plot handle), all 100 elements of x will point to the same plot, unless you reconstruct each object inside the for loop (like the second initialization example).
You can also look at modifying the behavior of the 'copy' method, as shown in https://www.mathworks.com/help/matlab/matlab_oop/custom-copy-behavior.html
