Fetching Item Tax rate

i have scenario where i want to fetch the Item Tax rate from Item tax templates where each template has single rate defined inside.
let me explain a bit.
in my quotation item table we can select item tax template for each item. i created a custom field below it with the name GST to fetch that template rate

I will have multiple tax rates and each rate will be defined in a separate item tax template.

one of the template details are below