NOTE: Fail2Ban is not avaliable on Windows platform.
I can't find ModSecurity or Fail2Ban management tool in Plesk GUI.
Security Core (ModSecurity and Fail2Ban) may absent because license key has no corresponding property or it was just not installed/enabled on server.
To check whether the license key supports it, go to
Server Management > Tools & Settings > License Management, and see if there is the line "Security core (ModSecurity and Fail2Ban)".
Fail2Ban component can be installed in
Tools & Settings > Updates and Upgrades > Add or Remove Components > Fail2Ban authentication failure monitor
ModSecurity component can be installed in
Tools & Settings > Updates and Upgrades > Add or Remove Components > Web hosting features > ModSecurity Web Application Firewall for Apache
ModSecurity component should be enabled in
[modSecurity] enabled = true