These steps should be similar across Red Hat type distros.
Before we proceed, lets stop SNMP
sudo systemctl stop snmpd
Disable SNMP Versions 1 and 2c
First we are going to disable SNMP v1 and v2c
You can manually edit the /etc/snmp/snmpd.conf file and comment out or delete every line starting with com2sec, group, access. Or you can run the following sed commands to change it for you.
sudo sed -i 's/^com2sec/# com2sec/g' /etc/snmp/snmpd.conf
sudo sed -i 's/^group/# group/g' /etc/snmp/snmpd.conf
sudo sed -i 's/^access/# access/g' /etc/snmp/snmpd.conf
https://serverfault.com/questions/376688/how-to-disable-version-1-and-version-2c-in-snmpd
Create SNMP Version 3 User
Follow the prompts to create a SNMP v3 user.
sudo net-snmp-create-v3-user -ro -a SHA -x AES
Start SNMP
sudo systemctl start snmpd
You should be good to go.
If you are running a firewall, you will need to allow an exception for SNMP, UDP port 161. You may also need to allow an SELinux exception. Check out the last portion of both these articles.