Each Laney CXP-112 powered monitor has a mono, 1/4" jack for connecting ONE external, unpowered monitor, of 8 Ohms or more.
Also: a mono, 1/4" jack designated as a Line Link, to provide line-level signal to another power amp and speaker(s), or powered monitor and external speaker. If a device connected via this link has a Line Out or Link, it can be connected to the Line In of another power amp and speaker(s), or powered monitor.
That configuration could be replicated/chained, ad infinitum.
If you’re referring to the typical PA board, or powered mixer’s Subwoofer Out: it would typically receive only Bass freqs, determined by an internal crossover.
Thus: not suitable for monitor use.
Far as wiring*: you’ll need 1/4" TS, instrument cables, for line level connections and (however many) 1/4" to 1/4" speaker cables.
*ie: https://www.amazon.com/dp/B081T2S74C/ref=vp_d_pb_TIER2_cmlr_lp_B073RMQKYG_pd?_encoding=UTF8&pf_rd_p=21b55c31-c104-4168-9e8f-9425024c3fcc&pf_rd_r=WPC4WVMJG18SX9J6SHEV&pd_rd_wg=6uZnk&pd_rd_i=B081T2S74C&pd_rd_w=N893z&content-id=amzn1.sym.21b55c31-c104-4168-9e8f-9425024c3fcc&pd_rd_r=c2d1bb50-df07-4236-9eb8-208c8a266320
and: https://www.amazon.com/GearIT-Premium-Speaker-Cable-6-35mm/dp/B08JVPNGPW/ref=sr_1_6?crid=2080FMP6J6NMP&keywords=1%2F4%22+speaker+cable&qid=1659484485&s=musical-instruments&sprefix=1%2F4+speaker+cable%2Cmi%2C101&sr=1-6
IF it was your intention: I don’t see a way to connect the CXP, powered monitor speakers, to the drum/keyboard practice amp, you’ve referenced. Only: a 1/4" jack, for an external, unpowered speaker.
