Since there is nothing out there in the USA on how to do it, here you go. I went from 5.7 to 8.0 so I can update to Joomla 5. Here is what I did to update and hopefully will make your life easier. I polished off half a bottle of Johnny Walker with the trial and errors, and the wait times.
In IONOS control panel under Hosting > Databases, go to your current database and click the 3 dots at the end under ACTIONS, select RESTORE DATABASE
NEXT: you will see BACKUPS click on it so it drops down to the date of the current day you are working on. so if you are doing this on Christmas, select dec 25. When selected then select the Download database backup. Give it a few and you will see a new page with the Download tab, click on it and download it to your PC
While it is doing that, you can back out of that screen and go back to databases. there on the top right you will see a button for CREATE DATABASE, Click on it then select the Standard database button. A new screen will pop up and you can choose between MariaDB10 or MySQL8.0. Add a description and password of your choosing.
Now there seems to be about a 30 minute wait before you can actually use your database but when you are ready or them, on the DATABASE home page, select OPEN for the DB you want to import the file that you saved to your PC previously. It will open a new window for phpMyAdmin
Click the database name
select import
browse the file that you saved and select it
scroll to the bottom
select go
Then hurry up and wait.
Your database will say success when done.
Go back to your database and it will say 0.0 GB of 2.0 used
This was another waiting game and by this time I was getting trashed so i came back in an hour and tried to change in the back-end of my joomla. Make sure Firewall and Gzip (in configuration) are off. then in the configuration section of the joomla backend add the info (click on the database you are working with under the database section- host, user name and db name will be available to you) from the ionos site of your database and save. Don't worry, if something is wrong with it, it will not work and you still have your current config and no issues with the website. I got a 2002 error and some other stuff, freaked out at first but a few sips later I retried and it worked fine. had me log out and I had to enter my credentials and it was updated, a quick hail mail, 6 our fathers and a double pour, I checked the site and it it seemed to work fine. As I was that guy that started with the MAMBO site to Joomla 1.5 to the joomla 5... it can be hit or miss.
Good luck, don't ask me any technical questions, I did this under the influence and will not remember tomorrow.
🙂
Jbx