There are 2 main options when anyone plays Portugal.
1: Conquer Spain, colonise like crazy.
2: Colonise like crazy.
That's about it.
Choosing option 1 will give you plenty of manpower, by obvious means.
Option 2 will also give u plenty of manpower, just that it's more tricky. For example, you have to colonise South America quick, getting all the grain provs fast, and try your best to keep the natives intact so the cities will be bigger. Bigger grain baskets in South America = higher manpower.
Heck, why would you need a 100K army if you're not gonna conquer Spain?
1: Conquer Spain, colonise like crazy.
2: Colonise like crazy.
That's about it.
Choosing option 1 will give you plenty of manpower, by obvious means.
Option 2 will also give u plenty of manpower, just that it's more tricky. For example, you have to colonise South America quick, getting all the grain provs fast, and try your best to keep the natives intact so the cities will be bigger. Bigger grain baskets in South America = higher manpower.
Heck, why would you need a 100K army if you're not gonna conquer Spain?