Forget the PRC.
The Philippines Navy wouldn’t last more than one engagement against either the Navies of Taiwan or Vietnam.
The Philippines Navy is nothing more that a maritime police force.
They have no ability to enforce any claims with the Spratly Islands.
The most important strategic ability the Philippine Navy supplies is military transport around the Philippine islands.
Its their amphibious vessels (also mostly very old) that make it possible for the Philippines to move significant ground forces (well, significant in Philippine terms).
They have vessels that can uniquely deliver significant cargoes to many islands and small ports with primitive facilities.
This is the principal value of a Navy in support of a basically counter-insurgency military in the context of the Philippines.
The patrol part of the Navy is indeed just a coast guard.
It would not really have an “engagement” with any enemy with semi-modern aircraft or antiship missiles. Its patrol ships would just be targets.