This answer might be phone-specific (my phone is an "Samsung Galaxy S21 Ultra") or Android version-specific, but I am posting this answer anyway just in case someone finds it useful:
I had a similar issue with a set of Bluetooth earbuds (Amazon ASIN B0BPS83P1W), namely this: Pressing the phones volume button to the lowest level (just one level above the level where the sound completely shuts off, or mutes the sound) results in the volume being still too loud for my ears. I observe that my pair of earbuds is likely different from the OP's earbuds (completely different manufacturer, etc.), so I reason this is an issue that must be rectified in the Android system via app or other means, and might not implicate the bluetooth earbud manufacturer.
I examined DavidEG's answer on 2024-01-27, and particularly the
SoundAssistant app mentioned in that answer, and found it was non-existent (browsing to that link resulted in "We're sorry, the requested URL was not found on this server."). I then searched through for other apps that might directly allow controlling the effective volume level and did not find any app (I did not purchase any apps but only examined cost-free apps) that could effectively reduce the volume level. There may be apps that can do so, but it was next to impossible to identify them without testing them all, which is prohibitively expensive in time-cost. Thus I gave up on that.
I then hunted through my phones built-in settings and found an Equalizer that seemed to work: I found that the levels for all of the frequencies could be lowered. In this particular use-case, I lowered all frequencies down to the same level, as I do not require amplification or attenuation of different frequencies but instead attenuate all frequencies.
The advantage of this approach is that it does not require installation of apps to address this issue only to find they come with other hidden costs such as ads. The possible disadvantage is that this may be phone-specific or Android-version specific, and if so, your phones customized version of Android may not have a/the so-called "Equalizer" setting.
Regardless, below I show the screenshots of how to navigate down to the Equalizer and lower the volume for all frequencies. Other phones may have similar means to lower the volume globally: