certbot -q renew --renew-hook "service nginx reload"

certbot

# /etc/cron.d/certbot: crontab entries for the certbot package
#
# Upstream recommends attempting renewal twice a day
#
# Eventually, this will be an opportunity to validate certificates
# haven't been revoked, etc.  Renewal will only occur if expiration
# is within 30 days.
SHELL=/bin/sh
PATH=/usr/local/sbin:/usr/local/bin:/sbin:/bin:/usr/sbin:/usr/bin

0 */12 * * * root test -x /usr/bin/certbot -a \! -d /run/systemd/system && perl -e 'sleep int(rand(3600))' && certbot -q renew --renew-hook "service nginx reload"

@Freekers correct. Although, down below on the same doc's page it says

--pre-hook PRE_HOOK Command to be run in a shell before obtaining any
certificates. Intended primarily for renewal, where it
can be used to temporarily shut down a webserver that
might conflict with the standalone plugin. This will
only be called if a certificate is actually to be
obtained/renewed. When renewing several certificates
that have identical pre-hooks, only the first will be
executed. (default: None)

So, will --pre-hook and --post-hook only be called if a certificate is actually to be obtained/renewed, not before and after every renewal attempt ?

Sounds like a renewal attempt is when a certificate is actually to be obtained/renewed. One would think that a check for whether a certificate needs to be renewed at this time is part of a renewal attempt. Apparently, not.
So, basically, the only difference between pre/post and deploy in that sense is based on a chance of renewal failing, not whether it was "required"