Try booting into Safe Mode to see if the Mac will finish booting. If the laptop boots into Safe Mode, then post several of the Kernel Panics logs here using the "Additional Text" icon which looks like a piece of paper. The Kernel Panic logs are located in "/Library/Logs/DiagnosticReports" where the file names begin with "kernel" and end in ".panic".
You may also want to run EtreCheck and give EtreCheck "Full Disk Access" so that the report includes extra information to provide more clues. Post the report here using the "Additional Text" icon which looks like a piece of paper.
If Safe Mode does not work and the diagnostics suggested by @a brody don't show a problem, then try booting into Recovery Mode (Command + R) or even better Internet Recovery Mode (Command + Option + R) and run Disk Utility First Aid on the hidden Container. Within Disk Utility you may need to click "View" and select "Show All Devices" so that the hidden Container appears on the left pane of Disk Utility. Even if First Aid says everything is "Ok" click "Show Details" and scroll back through the report to see if any unfixed errors are listed. If there are any unfixed errors listed, then you will need to erase the whole drive and restore from a backup or clone (Intel Mac, if you have an M1 Mac, then things are slightly different).
If you have the 2016 - 2017 MBPro 13" (non-touchbar) model, then perhaps your SSD is failing which tends to be common for that particular model. The best way to confirm is by the Kernel Panic log and/or booting off an external full macOS drive and see if the internal SSD disappears. Apple does have a free SSD repair program for a small number of those specific laptops.