Would it be possible to buy an external mic and plug it in the audio port but then be able to record audio through the microphone kn my camera app or not??
Yes, but you need an adapter. Regular mikes come with a standard 3.5 stereo jack, just like regular headphones. But the phone's audio jack expects a headphone-mike combo plug, so you need something like this to make it work: https://www.amazon.com/Rode-SC4-Microphone-Cable-Inches/dp/B00L6C8PN0 (search for "TRS to TRRS adapter")
