No one can accurately determine whether the data provided by the platforms are accurate because they are simply not subject to independent institutions exercising some sort of regulatory authority.
The best we can compare is the trading volumes on platforms that fiat money pairs such as the dollar, euro, and others.
For platforms dealing with cryptocurrencies, it is difficult to determine the accuracy of volumes based on the report provided by the platform.
If for anything, I'm sure the volumes on exchanges like Binance, Okex, Houbi are legit. Only small small exchanges will opt for faking volumes. I remember Hotbit and CoinOne faking volumes at some points between 2018 and 2019. Coinmarketcap.com actually has a filter
"Adjusted volume" . They say It reports the actual volume, different from the one reported by exchanges. I'm not sure about it though.
How can you be so sure that the volumes on this exchange are 100% legit and no small part of it are manipulated or over-exaggerated? maybe you should take a look at this article published by the
Blockchain Transparency Institute on their views of the top exchange they believe are clean from wash trading or fake volume, surprisingly binance does not make the list, while okex and bibox according to them are the highest in wash trading, this is their September report and i assume its accurate.