外牆根割一條，replace with solid beam and nail that into woodstud?

or https://www.homedepot.com/p/Stabilit-852-1-2-in-x-3-4-in-x-96-in-PVC-Composite-White-Outside-Corner-Moulding-10004-ZW096CB/205347157

? I can not add this later unless I cut and replace with something new.