I used to use a couple of apps like Cube ACR, or Call Recorder Pro, but these no longer work, and I'm skeptical of the workarounds to get them working again.
Given the new restrictions in Android 10, probably the way forward is a passthrough device which uses 3.5mm connectors to MITM the audio. I haven't found one which is a sure bet yet.
It's ridiculous both iOS and Android largely have no way to record calls/try to prevent it, especially when some of us live in jurisdictions where we are well within our legal rights do to that very thing.
Pixels don't have call recording enabled (in most regions?). It's frustrating that I'm forced to use a third party app to provide a feature that the phone app should have built-in, but Google decided I can't be trusted with.
EDIT: It used to be geo-blocked, now it's "This feature isn't available on Pixel."
That just gets me an option for "Start RTT Call". Nothing like call recording.
I'm on an S10e, which is not that new, so that could be part of it. I bought an older phone, because I really like my top grain leather case, so I wanted to get a phone which fit the case more than I wanted a more cutting edge phone.
It's inconvenient, but I've observed journalists who recorded calls by putting the phone on Speaker mode to increase the volume, and then used a second device (such as a laptop or iPad) to record the call.
Given the new restrictions in Android 10, probably the way forward is a passthrough device which uses 3.5mm connectors to MITM the audio. I haven't found one which is a sure bet yet.