Try visual methods and graphical signs.

Volatility of a time series is the unsteady and erratic movement in the series. It is often evident in a time plot of the series.

Dear Mr. Babak Jamshidi and Dear Mr. Ette Etuk .

I know what is volatility, and it is easy to distinguish it in a time series plot.

I want to see signs of the volatility "Clustering" in the time domain, which is also known as The "GARCH or ARCH effect". and it is expressed in literature such as: [ Engle, Robert F. "Autoregressive conditional heteroscedasticity with estimates of the variance of United Kingdom inflation." Econometrica: Journal of the econometric society (1982): 987-1007. ]