I recall having read about elections in Africa and the troubles they faced. I can't find it now, but there was one particular website offering a very detailed but rigorous approach to determining the legitimacy of elections. I'll offer this article from the BBC as a stand in for the criteria (from 2016):
https://www.bbc.com/news/world-africa-37243190
Vote rigging: How to spot the tell-tale signs
1. Too many voters
2. A high turnout in specific areas
3. Large numbers of invalid votes
4. More votes than ballot papers issued
5. Results that don't match
6. Delay in announcing results
I would encourage anyone from Venezuela to look into the history of elections in Africa. It is well documented and criteria well supported.