Hi,
Can I get 10G speed with Rj45?
Yes, you can get 10Gig, and you can connect any device (wireless, server, workstation, etc.) that supports 10Gig to the switch.
If you use cat6a and higher, the distance can be up to 100 meters using copper.
Multigigabit Ethernet technology: Cisco Multigigabit Ethernet technology allows you to achieve bandwidth speeds from 1 Gbps to 10 Gbps over traditional Category 5e/6 cabling or above. This technology addresses the need for exponential increases in bandwidth with the enormous growth of 802.11ac Wave 2, to be eclipsed by the growth of Wi-Fi 6 and new wireless applications without having to replace current cabling infrastructure.
datasheet:
https://www.cisco.com/c/en/us/products/collateral/switches/catalyst-9300-series-switches/nb-06-cat9300-ser-data-sheet-cte-en.html
HTH