Search Multiple ID's with Multiple Rows by Eloquent

I have one table which is used to get data combination of input data.like multiple molecule(chemical combination) as one combination.

Input

$id = $required->input('search'); // array:2 [ 0 => "3" 1 => "8"]

Case 1:

Table 1

id	refid	product_id	name	ref_2
1	1,3,46,7	5	test	6
2	1,3,8,90	10	test1	8
3	3,8,67	14	test 4	11
4	8,699,	19	test 4	11

query

$model=Model::whereIn('ref_id',$id)->pluck('product_id');

Fetch Product, query of combination contains id's 3,8

but it is fetching id's contains 3 or 8

Case 2

Table 2

id	refid	product_id	name	ref_2
1	3	5	test	6
2	5	10	test1	8
3	8	5	test 4	11
4	6	19	test 4	11

$model =MOdel::whereIn('ref_id',$id)->groupBy('product_id)->pluck('product_id');

Is this possible to do and is there a better method of doing this?

via Chebli Mohamed