I realized the equalizer preset is applied to any output devices, which is definitely not what we want bluetooth speakers and headsets. You can use the autoload folder in ~/.config/PulseEffects like so
~/.config/PulseEffects/autoload❯ cat alsa_output.pci-0000_00_1f.3.analog-stereo.json
{
"name": "librem14-eq-2.0"
}
~/.config/PulseEffects/autoload❯ cat bluez_output.C0_28_8D_F6_95_0B.a2dp-sink.json
{
"name": "default"
}
To create the default profile, just disable all effects in pulseeffects, then save this profile as default. The name of the file is pulse module name you want, which can be found by running pactl list