Is supplication via social media—in the form of "God willing, my Lord will send you joy and happiness...etc." in exchange for a like or comment—answered?

Sending supplications via messages is permissible. Scholars have mentioned that if a questioner sends their question on paper, they may attach a supplication to it. However, we must point out that the supplication mentioned in the question is forbidden because it is conditioned upon Allah's will, whereas the Sunnah is to be firm in supplication. There is no objection to conditioning a supplication upon a condition, but we do not see much benefit in that unless the content is something good to spread. It is not necessary for the supplication to be answered.