hI

As long as you have

minimum extent 128K clause

(dont confuse with minextents parameter, they are totally different)
all extents will be multiples of 128K no matter the size of initial and next.

I said when extent issue is done, it means after you have set initial next at tablespace level. When those are done the only thing we can change are pctfree and pctused parameters to accomodate updates/inserts/deletes (this is for both cases by the way)