Question How to get multiple OS on the 64 GB microSD card that came with my kit?

[Chasville]

I am new to Raspberry PI, but not new to building my own computers, so I have some ability. I got the iUNiKER Raspberry PI 4 B 8GB kit off of Amazon. I had to update the Noobs to the latest version. But then I found out that the default OS is 32-bit. I need to run a 64-Bit OS for the work I'm going to be doing on the PI. So, I've been reading some postings and they talk about imaging. But I remember reading somewhere before I got the kit that it is possible to have multiple OS's on the microSD card and then to choose which one to load, or something like that. I need more specifics. I can download the Raspian 64-Bit OS "image" file, but I'm at a loss of what to do with it to make it available on the 64GB microSD that came in the kit. Do I just make a file folder in the OS folder, and copy the image into there? or is the "img" file misleading me, and it is really just a set of files and folders that are in a file that is using .img as its extension? Is this really just a zipped folder name? I'd rather not buy a microSD card just to play around with. And I don't want to mess up the card that came with the kit. So, if someone with more experience can give me some better clues/directions than what I've found so far, that would be greatly appreciated.

 

[TerryLaze]

An .img (if it's not a picture) is generally a image of a system meaning an exact copy of all the info of a disk in a single file.
To use that image you would normally have to write it to an sd with a software like etcher and it would take over the whole sd, deleting everything that was on it before.

https://etcher.download/

You can also use this program to take an image of your current sd so you can write it back to the sd if anything should happen to it.
Or you can download the OS that is currently on your sd from the net to do the same.