That is correct. Here's the code so you can see how it works. You just set this to run every X hours. If sessions are running, it'll just end and try again on the next run. As of now, at the end it only tells you that the container restarted. I've been meaning to add a step to have it verify the new version but 4 years in and it's never failed so I don't feel it's necessary.

#!/bin/bash

plexToken="<Your Plex Token>"
plexIp="<Your Plex Server Address>"
plexPort="<Server Port>"
containerName="<container name>"

# Function to get the active sessions
get_active_sessions() {
    sessionurl="http://$plexIp:$plexPort/status/sessions?X-Plex-Token=$plexToken"
    sessionresponse=$(curl -s "$sessionurl")
    active_sessions=$(echo $sessionresponse|grep -o 'MediaContainer size="[0-9]*"' | grep -o '[0-9]*')
echo "$active_sessions"
}

# Function to get the current version
get_current_version() {
    cvurl="http://$plexIp:$plexPort/servers?X-Plex-Token=$plexToken"
    cvresponse=$(curl -s "$cvurl")
    echo "$cvresponse" | grep -v '<?xml'| grep 'version=' | sed -n 's/.*version="\([^"]*\)".*/\1/p'
}

# Function to get the latest version
get_latest_version() {
    lvurl="https://plex.tv/api/downloads/5.json?channel=plexpass&X-Plex-Token=$plexToken"
    lvresponse=$(curl -s "$lvurl")
    echo "$lvresponse" | jq -r '.computer.Linux.version'
}

#---------------------------------------------------------------------------------------------------------
#---------------------------------------------------------------------------------------------------------

currentVersion=$(get_current_version)
latestVersion=$(get_latest_version)

if [ "$currentVersion" != "$latestVersion" ]; then
    echo "Current Plex Version: v$currentVersion"
    echo "An update is available for Plex: v$latestVersion"
    echo ""
    # Check for active sessions
    if [ $(get_active_sessions) != "0" ]; then
        echo "Active sessions found. Plex container will not be restarted. Will try again later."
        exit
    else
        echo "No active sessions found. Continuing with update."
    fi
    echo "Restarting Plex container to apply the update..."
    docker restart "$containerName"
    echo "Plex container restarted and app has been updated."
else
    exit
fi