If a website offers every season of Family Guy for free on your iPhone, they are lying or stealing your data.
If you live outside the US, Family Guy is usually on Disney+ under the "Star" brand. Download Family Guy Episodes Iphone
An iPhone with 64GB of storage can realistically hold 4-5 seasons at a time. An iPhone with 256GB can hold the entire 20+ season library easily. If a website offers every season of Family