Rich formatting for text poppulating via if condition

Good day peeps, I am trying to do rich formatting within a text field which is generating text based on dropdown value selected. I want to text to be generated as:

HEADING

1) Specs

2) Summary

3) Multiple lines keep going.

var selectedPackage = this.getField("Equipment").value;
if (selectedPackage=="Tractor") event.value = "Heading in BOLD with center alignment, 1) Specs 2) Summary 3) multiple lines keep going.";
else if (selectedPackage=="Trailer") event.value = "Trailer also has detailed Specification in multiple lines.";
else if (selectedPackage=="Weigh Scale") event.value = "Weigh Scale also  has detailed Specification in multiple lines."; // etc.
else event.value = "";

Please let me know if I am not clear in my instructions. Any help would be highly appreciated.