While shooting any printout from any application , say for example , PO print , when a user goes to select the printer the whole list of printers appears , can it be restricted to a list of 5-6 printers where that person actually needs to print out in real time.

No, this list cannot be restricted. but you can restrict on which printer they can print using authorization object S_SPO_DEV. This way, they will still see all printers but won't be allowed all of them.... annoying but it works.

Probably a bit late for you now, but our printers in SAP are all named for the area they are located, e.g. a Corporate team's printer will start with CORP (CORP01, CORP02 etc)
So when using F4 a person can specify CORP* and see the printers for their area.
We only have 4 restricted printers, for cheques, invoices etc and we named them starting Z, assigned and auth group and then used the auth restriction to allow everyone to see printers A*  to Y*, and assigned access to the restricted using their name and auth grp. Staff without access to those printers can't see them in their F4 list.
 

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