If the barrel isn't marked you could find out with your cleaning rod.
Insert the rod from the muzzle end.
Put a patch in the patch tip and screw the patch tip into the end of the cleaning rod.
Pull the patch/tip through the chamber till it contacts the lands and stop.
Use a sharpie to mark the rod. Just a dot or hash mark will do.
Pull the patch/tip through till you see the mark come back to the same position it was in when you marked it and stop.
Use a tape measure to determine distance in inches from the muzzle to the mark you made.
That's the barrel twist in inches.
.223's used to be (long time ago) 1 turn in 12" or some were even 1 turn in 14". These were good for 55 grain and lighter bullets.
The 62 grain bullets prompted a change to 1 turn in 9".
The heavier bullets prompted a change to 1 turn in 7" and some are 1 turn in 8".
I actually have a heavy barreled AR15 varmint rifle (I called it the vARmint rifle) that has a 1 turn in 10" barrel. The only one I've ever seen with that twist rate. I don't shoot anything heavier than 55 grain bullets in it and it actually does very well with 45 grain bullets.
While the "rule" is not 100%, if you want to shoot the heavier match/hunting bullets that have been developed to try to improve the .223's performance from a varmint cartridge into a better man stopper/deer cartridge you'll most likely need the faster twist 1 turn in 8" or 1 turn in 7" barrels.
