A quick Google search suggested this app: https://play.google.com/store/apps/details?id=flar2.homebutton XDA also did a cover on it, but it looks like you'll have to enable developer mode for a moment to allow the app to read logs.
Here's what I can think of.
Only wifi and data are on all the time. NFC is always off, Bluetooth is off unless I'm in the car. Adaptive Battery is on and I restrict background battery for as many apps as I can. Only Messages and Gmail can use background data. All animations are turned off (under Developer options). I don't know if this helps, but I clear apps (swipe up on the white pill) pretty often. Connect to charger when streaming long shows and movies. I don't have any screen-intensive games. Adaptive Brightness is on for the screen. Brightness is 52%.
That's all I can think of, if I think of more I'll add it. AccuBattery shows more detailed usage for apps that can help fine-tune things.
Attention all pixel 3xl users, I have found a solution to the issue. The buzzing is generated from frequencies between 20-500 mhz. So I found an app that allows you to control the amount of sound coming from each frequency. So I would recommend sliding down the second to left most slider in the equalizers a little bit in order to reduce the buzzing, and you can adjust to your liking. I bid you adieu. https://play.google.com/store/apps/details?id=com.kodarkooperativet.blackplayerfree
I use the app 'Granular Immersive Mode' for stuff like this. It allows you to specify if the navigation bar should be hidden or not, or let the system decide. If it's hidden, you can swipe it up to show it.
Here's a link to the app: https://play.google.com/store/apps/details?id=com.rascarlo.granular.immersive.mode
You will need to give it permissions though via ADB, but that's pretty easy and there are guides for doing so.
Also, download this app (or a similar one) and test your FP sensor to make sure it's working: https://play.google.com/store/apps/details?id=com.appbusters.robinkamboj.senseitall&hl=en_US
I totally recommend Swift Black or a substratum equivalent. I run Swift and it works very well.
Probably easier ways to do it than this, but here's how I do it. Grab a file explorer like Solid Explorer, once installed, just take a quick peek to make sure you can find your ringtone. Next, go like you're setting your ring tone, and when asked how to browse for the sound, select Solid Explorer and then choose your mp3.
Dome Glass Google Pixel 3 XL Screen Protector Tempered Glass Shield, [Liquid Dispersion Tech] 2.5D Edge of Screen Coverage, Easy Install Kit and UV Light by Whitestone for Google Pixel 3 XL (2018)
https://smile.amazon.com/dp/B07KCQQVXM/ref=cm_sw_r_cp_apa_i_t9njCbGPZD892
Wierd installation but it sits perfectly and no issues using the screen. The cost is high but no bubbles and no raising edges due to the epoxy glue.
Well I'm a big MNML and Bear Motion fan. But no BM case yet, and the MNML was just too slick for an XL and my small hands. So I found this ESM TPU case and it's refreshingly THIN. Great grip. However when I went to my orders cart to find the link it says it will be released August 2019! Which is odd because I obviously have one now.