hello, do you use any tools to monitor the temperature in the rack, power consumption, current CPU consumption, temp, etc. and display it on an additional screen

I use a combination of all the things people have mentioned here, IPMI (iDRAC), SNMP, NUT for UPS's and Aqara temperature sensors in the rack all feeding into Home Assistant which has a separate "System / LAN" dashboard with pages for different hardware, etc.

I have an APC metered PDU (AP8870) that gives me power, temp, and humidity stats for the rack