Voice recording on Xiaomi Redmi Note 5 Pro

[aix123]

It's a new phone and I've never used a voice recorder on a phone before. I want to record, at a reasonably good quality, a conversation with a friend. I intend buying a plug in mic and adapter cable. The built-in recorder app is pretty good, but I wondered if another app will provide even better sound recording quality. Or is that not possible? Is it limited by the hardware?

(Also, despite looking online, if not using a plug in mic, I can't work out where the built-in mic is on the phone.)