if a field is multi select, can you separate them on a saved search? for e.g. field has 1,2,3,4 values in one field but i want to see them in 4 different rows.

Idk your use case. But if you just want visualization then you can use a formula html field and seprate the date by comma and add br tag to afterwards. Otherwise if you want separate rows for some reporting purpose then you might have to handle the use case in excel itself.

I need to bring that value in the custom field and it is multiselect field, so i need to create different line

You want to do csv upload and set the existing multi select field value to a different multi select field ? Is that what you mean ?

no, this field is dependent on sub customer field, each sub customer can have their own card. for example sub customer A has card 1 and customer B has Card 2, they both are selected in the same field, so i need to separate them in the saved search

can you try SPLIT formula?

I will ask her, thanks @Sam-I-Am