If for some reason you don't have the adaptor, Google sells the piece ... that phone appears to feature a headphone jack. There's no news yet on whether the upcoming Pixel 4 will have a headphone ...

The mysterious code name of Google Pixel 3a XL is Sargo. The phone is powered by Qualcomm Snapdragon 710 with a 3.5mm headphone jack. The smartphone comes with a size of the display is 6.0 inches ...

Otherwise, the Pixel 3a offers many of the same features as the larger model including on the camera, Call Screen capabilities, headphone jack and ability to trigger Google Assistant by squeezing.