You can´t find the PDF icon in Manage Purchase Orders app Output Section
SAP S/4 HANA Cloud 2108
Reproducing the Issue
App Manage Purchase order--> Output Management
Please click on the button 'Show Details' then you will be seeing the PDF icon.
By default it has a lower sequence - if you'd want to make it display without clicking on the 'Show Details', please click on the gear button and adjust the 'Display' to a higher order.
KBA , MM-FIO-PUR-PO-OM , Purchase Order Output Management , How To