I'm not sure if I can accept that amount through Paypal without paying a huge fee.
You mean outside the STANDARD fee of Paypal? It is a lot of money.
* Standard international wire transfers. They often ahve excessive high start fees, but for that amount a wire is pretty much standard.
* You may use a third party payment service. Paypal is among the most expensive ones. Google is your friend. Without KYC etc - 100k is a LOT to run outside of normal banking. You do have a bank account, right?
Would also be great to know what to expect in terms of tax
Noting special. Which means standard income and business taxation as per your busines licesnese and philippines tax code apply.
You DO have a business license, right? 100k USD is way above what you likely can slip in as "small income" given it is on the top tier of the yearly income in the philipines. Heck, you may realize that you pay top income taxes anyway and no, you CAN NOT just hide the money. This is major tax fraud.