Can we create line graph with combination of dashed and solid line as per x-axis zone wise, for exaample after 8 point there will dashed line, else solid line

Nope, not supported in the current version (3.6.5) of ApexCharts.
Is this feature support available in the new versions?
I did it creating two series, in your example, one from Jan to Sep, other from Sep to Dec and then setting different strokes for each one. It's not perfect but it's a cheat ;-)
Most helpful comment
Is this feature support available in the new versions?