It will be very difficult to upgrade a fresh installation from the 2020 Manjaro ISO that you currently have. There have been so many updates and changes since then that you will likely have a large number of software conflicts and a lot of manual maintenance to do.
You would be much better off downloading the newest release of Manjaro from Download x86 – Manjaro and burning it to a bootable USB (you can do that on your non-updated system by following the instructions at [HowTo] Write a Manjaro ISO to an USB stick with dd - Contributions / Tutorials - Manjaro Linux Forum). You can then use your newly created USB image to install Manjaro’s 2024 release.