A back up for safe keeping.
This was my plan when I cloned my Windows laptop drive to a USB memory stick when I went trekking in the Himalaya.
I wanted an option to boot my laptop from USB into Windows, if the internal spinning hard disk failed (a distinct possibility in rough terrain). It can be difficult to disassemble a laptop in adverse conditions to replace a dead drive, assuming you've taken a spare.
A WinToUSB bootable USB clone allowed me the option to continue backing up hundreds of GB of RAW + JPG files with relative ease.
Most of my clones these days are performed using Macrium Reflect and then I swap the source and destination drives internally. However, I still keep a WinToUSB memory stick handy to boot the occasional faulty system.
I really can't see all of the BIOS screen because of the resolution .
It seems your computer's graphics output is set to a resolution that's too high for your TV which is acting as a monitor.
Please can you tell us the manufacturer and the model number of your TV/monitor.
Also, do you have the exact model number for your computer (and your graphics card too if you have a discrete card).
The whole of the BIOS screen should be readable, but perhaps your TV is an old (low resolution) device or your video cable is incapable of working at the TV's maximum resolution.
Do you know if the cable between the computer and the TV is:
1). HDMI
2). DVI
3). DisplayPort
4). VGA
5). Something else?
https://en.wikipedia.org/wiki/List_of_video_connectors
Ideally, you should try another monitor and see if the whole BIOS screen becomes visible.
If you're using a very old HDMI cable, it might be worth trying a modern cable. It tends to be the more esoteric UHD/4K high refresh rate resolutions which don't work on ancient HDMI cables, but that's usually only after you've booted into Windows and if your graphics card supports 4K/UHD.
i used a USB 1TB external drive.
If you managed to successfully clone your C: drive to the 1TB external drive, then if your internal C: drive becomes corrupted, remove it and fit the 1TB drive in its place. If you're lucky, the PC will boot up (albeit more slowly?) from the 1TB drive, when it is mounted inside the computer.
That's the general idea behind cloning (when it works). You are making an exact copy of your existing bootable drive.
What you do with the cloned drive is a different matter. You can clone a old small drive to a new much bigger drive; useful if you're running out of drive space. Alternatively, you can keep the cloned drive securely for emergencies (see below).
A cloned drive is a snapshot in time. If your clone was created exactly one year ago and you swap it for the current drive, your computer will move back to January 2024 and everything you've done since then will vanish. That's why you should regularly copy all important files to at least two other devices (ignoring any clones).
Backup to external hard disks, portable SSDs, USB memory sticks, another computer, even the Cloud. Just make plenty of backups.
You can reinstall Windows and programs relatively easily on a new drive in a few hours, but you cannot get your data back if you don't have a working backup copy (or two).