Upgrading from that long release, you will likely need to do a manual upgrade anyway because 4.5 is not compatible with PHP 8 and 4.7 is not compatible with PHP 7.4 so you're in a bit of a pickle.
What I would recommend
Turn your site offline.
Do a complete backup, files and database. Contact your host to ensure it's there and up to date when you turned your community offline so you don't lose any data/posts/etc... Not to be rude to hosting providers but seen a few clients get hosed so relying on your host sometimes can get you into trouble.
Disable all third party applications and plugins. Switch to an unmodified theme.
Download files from the Client Area (don't upload yet).
Switch to PHP 8, check to ensure you have all modules enabled: https://invisioncommunity.com/files/file/7046-invision-community-requirements-checker/
The files you downloaded from the Client Area, extract those to your computer and upload the contents of the "ips_***" folder to your server, overwriting what is there.
Go to [your community's base url]/admin/upgrade . Run the upgrader.
Upgrade your third party applications, plugins, themes to be compatible with the Invision Community and PHP versions. Investigate these to ensure they are compatible with PHP 8 before you enable any.
Check everything and open the community back up 🙂 .