In my opinion, as far as using the built-in microphone, it could depend on the phone model.
My three phones showed different results.
This shows how the bass frequency response changed before and after the RC run.
Before RC (NO EQ)
View attachment 9409
1. LG V60 (Harman RC)
View attachment 9410
2. Xiaomi 12T pro (Harman RC)
View attachment 9411
3. Xiaomi 13T pro (Harman RC)
View attachment 9412
The results for the V60 and 12T are very similar, flattening out the
75 dB 75Hz hump. The 13T, however, does not. The 13T has a MediaTek SoC while the other two are Snapdragon. Perhaps this could be a factor, but I don't know.
Also, it was uncomfortable on my speakers as it (excessively) rises along the Harman curve down to 45hz.
Finally, this is the result of my manual adjustment in WiiM PEQ. (Sub is included.)
View attachment 9413