I'm writing from the USA, but I work in IT and some things are pretty universal. Skills for IT is one. Things you should try to learn if you want such a job:
Cloud software such as Google Workspace and Microsoft Office 365. Tons of companies run on these.
Basic network troubleshooting. You should know what DNS is. You should be able to setup a networked printer and point machines to it. You should know how to point a machine at a shared network drive. You should be able to explain concepts like DHCP.
Windows troubleshooting (most orgs are Windows-based). How to troubleshoot software by repairing or reinstalling. How to get to system files that might help fix an app by deleting them to reset the app to it's default state.
The above will maybe help you get a foot in the door. Other things that definitely wouldn't hurt: VOIP systems, Windows Server, Active Directory, Group Policy, Microsoft Exchange, PowerShell, virtualization (VMware, Hyper-V). After that you can go down all kinds of specialization rabbit holes. I worked at a place that mostly supported architects. We had to learn how to troubleshoot CAD software and 3D rendering apps. That won't be useful most other places, however. But a lot of this can be taught at the job if you get hired as a level one tech, so don’t let that daunting list of scary sounding items frighten you away.
I don't know if Managed Service Providers exist in the Netherlands. These are firms that do IT for small and medium businesses who can't justify having in-house IT. Getting a job at one of these will speedrun you across a lot of tech as different clients use different tools. It's a great way to get exposed to both of the dominant cloud services mentioned above. After that, try to work at a larger org with dedicated IT. It's much simpler when you only have to support a limited number of solutions.
You can look into building a homelab. That's where you test out and learn the skills above by building your own infrastructure. There are homelab communities and YouTube channels and the like. It's a fun and addictive hobby if you enjoy these sorts of things and the feeling of accomplishment from implementing a technology that you learned on your own devices.
Happy to answer additional questions as needed.
Good luck!