yeah, that would require a rooted phone or something... there is EQ for at least some phones, i'm pretty sure... just look up equalizer in play store i'm pretty sure you can find them... some phones have a programmable button that can be set up to activate a specific app, sometimes with short and long press options... my old Blackview BV6000 had this feature, that would bring up the EQ app fast

oh yeah, i found a whole bunch, one called "booster" which makes it easy, you just set all the bars down except for the oners around that range i said (around 5000hz) and it sounds like a shitty telephone mic

also, the shortcut... many recent phones, since android 11 i think, have an "assistant button" and this is one app that lets you set a custom assistant that changes it to just be an app launcher https://play.google.com/store/apps/details?id=host.stjin.assistantshortcuts&pli=1 and another "button mapper" https://play.google.com/store/search?q=button%20mapper&c=apps

though tinkering with that i couldn't get it to actually recognise the "assistant" button

there is also accessibility buttons, which are floating overlays that you can tap that do things too, i think if you search you will find one or other options that will work so you can just hit one bututon and bam, crappy audio