Can you turn off HEIC and take regular old fashion phots (JPG/PNGs)?

• I don't need my photos to take on video characteristics. If I want videos, I will set the camera on video. How do I make my IPHONE 12 Pro Max camera take good old fashion jpegs or pngs so I don't need to convert them?

• Since it appears that to use the HEIC photos that I have already taken as I would a JPG they need to go through a conversion process. Do I have to buy an app to do this and if so, what is the best app to buy. Has Apple created an app for this purpose? If so, what's it called?

Thank you for your thoughts and advice.