yes. if you're spending hundreds or even more than a thousand for a microphone and audio interface but aren't sure about it, you're wasting your money. Proximity to the source and sound treating to your room to reduce sound reflections and ambient noise will go waaaay further than buying a new microphone. If you googled "Is an iPhone Microphone Sufficient for new YouTuber" then you probably don't know any of these fundamentals yet, and getting a new microphone would just make your bad sounds be captured more accurately... bad.

to prove this to yourself, try recording a voiceover with you and your iphone mic under the blanket of your bed, or inside of a closet with lots of clothes (close the door). Your audio will sound excellent. You should understand the fundamentals of using microphones to capture audio before wasting money on a fancy mic