Add into /etc/skel/.bashrc the following line before starting with the creation of any users on a new system.
export HISTTIMEFORMAT="%d.%m.%Y %T "
After this, your history lines will look like this:
[root@plaun-test42 ~]# history
…
1018 19.12.2020 08:45:01 groupadd -g 7000 paul
1019 19.12.2020 08:46:01 useradd -u 7000 -g 7000 -c 'Paul from IT dept' --create-home --shell /bin/bash paul
1020 19.12.2020 08:47:01 passwd paul
…
Another possibility would be to create a file like custom_historyformat.sh in /etc/profile.d and put the following text into it:
[root@plaun-test42 ~]# cat /etc/profile.d/custom_histformat.sh
#!/bin/bash
HISTTIMEFORMAT="%d.%m.%Y, %T "