Updated 04.13.2023 I've added a .stl file for the X1C that avoids the extra purge line in the rear left corner of the machine.  You'll need to run the print without the automated flow calibration.  Use a known calibrated filament profile and turn the flow calibration off so as not to interfere with the test pattern.

I have several Bambu Lab P1P printers, these machines are truly wonderful consumer devices that have set the bar high for the competition.  As a start-up I'm sure Bambu Lab is rapidly chasing down the various production and software issues, that are bound to arise.  Unfortunately, I am one of the many users who received machines from the factory with warped print beds. While my support ticket awaits its turn in the que, I decided to make up this simple first layer test to determine the actual usable print area of some of my Bambu Lab P1P printers, so that I could arrange some of my less critical (non-engineering) parts in optimal locations.

This is a first layer test, not unlike many other first layer tests for other printers, I've just formatted this array of 30mm square patterns to fit around the P1P excluded bed areas and linked them for easy removal and additional print verification.

Running this first layer test on your Bambu Lab printer will display how well the Automatic Bed Leveling system is able to compensate for the warped areas of the bed.  In my case, the bed is very dish shaped towards the middle and, predictably the ABL cannot adequately compensate near the perimeters of the bed.  The test shows however, a good bit of the bed is usable for smaller models that will not fill the entire print volume.  In my case, I found that a 200mm square area centered to the bed, was well compensated for and usable for non-engineering grade models… Optimistically I await a resolution from Bambu Lab to deliver a flat build surface for their otherwise excellent machines.

The attached pattern measures 253x253mm and is notched to avoid the default P1P and X1C bed exclusion areas.  You'll want to add it to your slicer centered on the print bed.  I've also included the Bambu Studio project, with the .stl already attached and setup for slicing with Bambu Lab Matte PLA.