not sure what the .pac files would be, since it's from a spin-off game of the Ridge Racer series, Critical Velocity for PS2 only and japan exclusive game. but I can guess it's an archive file. don't know about .irx and .32

 

sample files pac: https://mega.nz/file/gCIEQA4Y#T3hZkv_NXb4tk-hWJ7P-4UW0NltxnzWtGqMBmltFLkg
sample file irx: https://mega.nz/file/gHhA3AqR#fFMGMbqp_VUS-vjuMSNg5bhNyMJeJmoGaqreyqt8XVQ
sample file .32: https://mega.nz/file/pf4liRIK#p_addeoKoPFC-7oa009KG8Y_jGHH37fr3RejC32A2Vc

Try this script to extract data from PAC archive
https://github.com/bartlomiejduda/Tools/blob/master/NEW Tools/Critical Velocity/Critical_Velocity_PAC_script.bms

IRX/32 files are just PS2 executables.