Is it true that articles cited in Wikipedia get more citations? It is famously known that “visibility” of an article influences its citation count. Is it true that articles cited in Wikipedia page get more academic citations?
There appears to be some literature comparing citations on Wikipedia to citations in academic journals, but I have not been able to find any randomised controlled trial (RCT) on the matter.  For example, in a comparison of Wikipedia citations to journal metrics, Nielsen (2018) found that "[t]he Wikipedia citation numbers showed high correlation with the [Journal Citation Report's] numbers for the total number of citations to a journal" (p. 4).  If go broader than Wikipedia, Lawrence (2011) finds that free online availability is positively correlated with citation rate.  Both of these studies use observational data and show correlation between the outcomes, but they do not rule out other causal relations that would lead to correlation (e.g., if papers are more likely to be made available online, or added as citations in Wikipedia, if they become more cited).

If there are any enterprising researchers reading this post, this sounds like a good research question for a randomised controlled trial (RCT).  Since Wikipedia can be edited with a free account, it should be possible to set up an RCT where you add a randomised set of presently uncited academic articles to Wikipedia and track their citation progress in academic journals against a control group.  First find a set of articles relevant to a subject that are not presently cited on Wikpedia; then randomise them into a control group and treatment group, and add the articles in the treatment group into Wikipedia articles; then watch changes in the citation count in the academic journals over time, and then test for a difference in the groups.