When I flush the toilet there is a high pitch sound and it continues until the tank is full.
Is this air in the line if so how do I fix it?
Court

The noise is caused by your fill valve. You can clean or repair it, but its also cheap and (usually) easy to replace the complete fill valve and be done with it.

Yes, 99% of the time it's a fill valve. Easy DIY job.

Is this air in the line if so how do I fix it?
This isn't caused by air. Something's in there we must remove. Which ballcock is yours? Back to you, Tom