Found the exact scope looking for
Go to "cart price rule"
1- Create new rule (Add required values and status as active)
2- Go to "Conditions" choose "Products Subselection" > mention quantity as "equal to greater than (XX)" (in my Case value is "30")
3- Add "Category is (X)" (in my case id is "3")
Go to "Actions"
1- Select "Percent of product price"
2- Add "Discount Amount : (X)" (in my case 5%)
3- Go to "Apply the rule only to cart items matching the following conditions (leave blank for all items)."
4- In Drop down choose "SKU"
Select Required SKU's of Same category
First Rule is applied.
Duplicate Above Rule
Go to "Conditions" change the quantity as "equal to greater than (XX)" (in my Case value is "60")
Change ""Discount Amount : (X)" (in my case 10%)
Enable Discard Subsequent Rule and Save. both Rules are applied
Unfortunately in my Case 2nd rule is not discarding the rule 1. so i have done some mathematics and use "5.263%" instead of 10% in Actions > Discount Amount.
Its working perfect. If any one can help me in Unfortunate please advise.
1- I have added multiple products from all categories in store (i.e. 60 Products from other 10 Categories in store) and 29 Units of different SKU's from Category Id 3.
Discount Was not applied.
When increased any of SKU from category id 3 to +1 (29+1) and updated cart. 5% discount was applied till adding 59 No. of units of Different SKU's from Specified Category.
Discount value was only applied to the total value of 30 Units (Explanation: Discount was not applied to the whole cart)
2- When No of units reached 60+ Discount changed to 10%.
Thanks to https://magento.stackexchange.com/a/219725/62614