I am would like to create a regression model with different variables however before using these variables in my regression model I would like to transform the variable in order to make it more stationary .The variable that I would like to transform has time varying volatility . So far I have used different scaling techniques to transform my variable but I have not gotten the most desired results .
This is what my variable looks like plotted
As one can see the variable has time varying volatility , what techniques can I use to better transform my variables specifically variables with time varying volatility