The mic inside the camera is fine, the same Panasonic electret element used in $5 and $300 mics. The problem is the location and no mic is going to capture quality sound unless it is in position to "see" direct soundwaves from the source in at least a 90% direct to reflected or ambient sound level. So if your sound source is 10 feet a way, no mic is going to perform well, 20 feet, forget it. So the question ism how to get close, and the best way if one does not have a boom operator and Fishpole overhead mic is to use a wireless mic clipped to their collar. There are a lot of wireless mics and for most purposes they need not be expensive. There are transmitter and receiver pairs on eBay or AliExpress for $20 that would work better than a $5000 mic 10-15 feet away.
If there is a single source, you are can use a really simple system. With multiple sources, such as 2-3 people talking, you are into more complexity. You need to actively ride gain of each mic channel on a mixer or set up a small track digital recorder and balance them in post processing.
You need continuous sound and the video clips will be laid down on that continuous audio track since the sound can continue when switching to other camera angles or laying in B roll, or close ups. The sound would be in chopped bits if recorded in the camera as it is started and stopped for shooting position or angle changes. You can record additional audio tracks later but balancing them with the ambient room sounds of the other clips is not easy so plan the shoot out well dp thee sound track is original. IF you must add dialog later, it is best to record a could minutes of ambient sound so that can be mixes with the additional dialog so it had a similar ambient sound by making a copy of the ambient recording and laying the new dialog over it.
There are a lot of companies selling "video mics" that mount on the shoe but they are poor is the source is further than 3-4 feet away from the source.
Knowing what different polar pattern mics are good for and what negative indicators they all have,takes some experience but all that becomes unnecessary when micing close. In my 3 studio complex I had $500,000 in mics and now some of those have increased 10 times their new prices. so maybe the vintage collection if still together would have been well over a million....but none of that is needed or would be helpful in being the the solution if mics are close. All of those mics were the best solution for some application, and none were good for all of the applications
If you describe your production plan, cast count, distance from visual perspective, atmosphere, more specific information can be relayed.