1. pc on
2. usb-a to pc
3. pixel 4a on
4. plug in usb-c to pixel 4a
5. swipe pixel 4a down from top.
6. You should see "Android system • charging this device by usb" TAP THIS one line message!
7. A second two line message should:: appear:
"Charging this device by USB"
" tap for more options".
8. A "usb preferences" page appears. Only one change is needed! Look in the lower button group labled "use usb for:"
Click the radio button "File Transfer / Android Auto".
Thats all there is to it. File Explorer should now open automatically preset to the Pixel4a folder. Your files will be in the subfolder "internal shared storage"
Pretty straight forward from there.