Kyle, yes sir, the S&W CSX will handle +p ammunition just fine. As with any manufacturer they recommend limited use since it can wear parts quicker than standard velocity ammo but unless you're shooting thousands of rounds of +p ammo threw it I doubt you'll notice a difference vs standard velocity ammo. Hope this helps.

Well, I was gonna answer too BUT, the guys here already have you covered with proper info!!
Take care and good luck with your future purchase!!

Kyle, according t the owner's manual, yes.
“Plus-P” (+P) ammunition generates pressures in excess of the pres-
sures associated with standard ammunition. Such pressures may affect
the wear characteristics and may result in the need for more frequent
service.
Do not use +P+ ammunition.

Kyle, yes Sir. The Smith and Wesson CSX is compatible with +P Ammunition. Just increase firearm inspection intervals and you will be fine. Cheers and stay safe!

YES for +P. NO for +P+. But If you shoot a lot I would not use +P they do cause more wear on your gun and malfunctions for short barrel weapons such handguns or the CSX with its 3.1in barrel etc, these rounds are more for longer barreled guns, Subguns or PCC's etc. Even then many manufacturers do not recommend it. IE HK for my SP5's or SP5k's they do not recommend it either. From S&W:
"“Plus-P” (+P) ammunition generates pressures in excess of the pres-
sures associated with standard ammunition. Such pressures may affect
the wear characteristics and may result in the need for more frequent
service.
• “Plus-P-Plus” (+P+) ammunition must not be used in Smith & Wesson
firearms. This marking on the ammunition designates that it exceeds
established industry standards, but the designation does not represent
defined pressure limits and therefore such ammunition may vary signifi-
cantly as to the pressures generated and could be DANGEROUS"

yes it is +p rated however from the owners manual “Plus-P” (+P) ammunition generates pressures in excess of the pressures associated with standard ammunition. Such pressures may affect
the wear characteristics and may result in the need for more frequent
service" See page 11 smith-wesson.com/sites/default/files/owners-manuals/CSX_Pistol.pdf