Can a primary teacher teach KS 3?

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Am toying with the idea of applying for a new job ( obviously no guarantee I'd get it!)

Have always worked in primary, mainly top end of KS2, but the new post will involve teaching only one subject mainly within KS3. Can I wing it? My subject knowledge is probably patchy but I could read up on the area and refresh my understanding.....or can I? Is this done these days?

I think I have quite a strong application but am now worrying!

I trained and taught KS 3-5 for 5 years before getting bored of the teenage/ exam board stuff. So changed to teach KS 2 and 3. Only teach one subject to still in my comfort zone.
As long as you can prove you know what you are teaching you can teach any key stage. When a head if department I had a teacher who was primary trained teaching KS 3 and 4 history.