what version are you on now?

The website in question is on version 5.5.2... so it's not too far off according to the message saying the latest is 5.5.2.1.

I do have other websites that need updating as well but not sure of the versions without looking at them...

The other sites are saying the following:

Currently running version 5.5.2.1 and the latest version is 5.6.3.5

Another is similar with running 5.5.2 and latest version is 5.5.2.1

Same for another one as well... find it interesting that one site is a different version completely from the rest... does that have something to do with the Concrete Theme being used?

you can see all the version here:https://www.concrete5.org/developers/developer-downloads/...
but you may have to do incremental steps. You should be able to get to version 5.6.3.5 which will run on php 7.

To get to version 8 is a giant leap for there.

So to be clear on this fact... one must do all the incremental updates to get to a certain version and not simply jump to "the latest" or desired version such as going to 5.7.0 from 5.5.2, correct?

For clarity...
Sites that are running on any LEGACY version prior to 5.7 (5.4, 5.5 and 5.6) can only upgrade to 5.6.4.0.
There is no upgrade path to go from any LEGACY version to 5.7 or Version 8.

To go from using a LEGACY version to 5.7 or Version 8, you have two options...
1. Attempt to export as much data from your old site using the appropriate 'Migration' addons and attempt to import the data into a new install of Concrete5.
2. Rebuild your site from scratch on a new install of Concrete5.

NOTE - Although upgrading a legacy site to 5.6.4.0 will allow the core to run on PHP7 it does not mean the addons and themes will be PHP7 compatible, this is often where most work is needed in debugging site upgrades.

if you download those archives from the legacy downloads page you can upgrade manually after ftp'ing them into your site root.

Instructions here:https://legacy-documentation.concrete5.org/tutorials/manually-upgrad...

If the Concrete websites are connected to the Concrete community site, will that support them automatically updating to the latest version? Or is user intervention still required?

My concern is I tried an update on one site a year or so ago and it messed up the site to where I had to recover it... Really scared me... but don't remember doing the update the way you mention... Sure seems like there is a lot of updating to do... I will take a look at it...

connected to the community won't help with the upgrade AND all of the addons are not for sale anymore. So don't expect to get support unless the developer is still active in the community.

Also, if you can use cpanel to archive your site and db before you attempt upgrading, that is ideal. Additionally, put your site in maintenance mode during the process.

5.6.3.5 won't run on PHP 7, you must go to 5.6.4.0 for that.

Thank you for letting me know that...