Is number of battery charge cycles used available for me to view on my iPhone 12?

It is, but not by default. In order to view the cycle number, you will need to enable your iPhone analytics with Apple. It will still take a few days before the cycle count will appear. As you will find out, it will not be very intuitive ... but it is still available.

Alternatively, you can use an app, like coconutBattery, which will be far simpler.

If you want to go ahead with this, then just do the following on your iPhone:

1. Tap on Settings > Privacy > Analytics & Improvements
2. Enable the "Share iPhone & Watch Analytics" option. You do not need to enable any other option here.

After a few days, to view the cycle count:

1. Tap on Settings > Privacy > Analytics & Improvement > Analytics Data.
2. Scroll down until you find a file that starts with log-aggregated. If there are multiple files, select the one at the bottom as this will have the latest data.
3. The file will open with what looks like a number of lines of code. Tap anywhere on the code to access the selection tool.
4. Drag the tool to select everything in the file.
5. Tap on the selected portion, and then, choose Copy.
6. Launch the Notes app and create a new note. Tap anywhere in the blank note, and then, choose Paste.
7. In the Notes app, tap on the three dots in the upper-right corner to access the options. Select Find in Note.
8. Type in: batterycyclecount
9. You should be taken to that location where you should now see the battery cycle count. Makes you glad you used coconutBattery instead ... huh? ;)