You’re pretty close. At this point, personally I think it would be totally fair to look at the third solution or the advanced solution in this thread
https://forum.freecodecamp.org/t/javascript-performance-measurement-variability/394059
The big changes I would make are setting
numbers = Array(num).full(true);
(array allocation with a push is slow)
Initializing a sum = 0 outside of the first loop and replacing the reduce with a sum over the rest of the values
(you are already iterating from 2 to sqrt(num) so you might as well sum up as you go)
Put the j loop inside of the if statement for numbers[j] === true
(if j is composite, then all multiples have already been marked. All multiples of 6, for example, are also multiples of 2 and 3)