I recently had eyelid surgery. Now my eyelashes are twice as thick. Could this be an awesome side effect of the procedure?

Those two things are unrelated. Eyelash thickness and eyelid surgery don't have a connection positively or negatively

Thickening of the eyelashes following surgery is very rare. In fact, the opposite, thinning of the eyelashes, is frequently seen. Both are likely to be temporary. Trauma may  stimulate growth of hair follicles which likely results from the same effect as the drug, bimatoprost (Latisse) which causes all of the hair follicles to be in the growth phase (anagen) at the same time.