SARIMAX with seasonality greater than one year I would use Statsmodels SARIMAX with data having seasonality greater than one year.
In my case, I have seasonality equal 4 years, therefore I have tried:

smt.SARIMAX(endog, order=(p, d, q), seasonal_order=(P,D,Q,4))


Is it correct set seasonality = 4 when the seasonality is equal 4 years?
From the documentation of statsmodels:

s is an integer giving the periodicity (number of periods in season), often it is 4 for quarterly data or 12 for monthly data. Default is no seasonal effect.

So it depends on how you have your data recorded, if each entry is a year, your seasonality would be 4, however if you have monthly data, then it would be 36.