It’s important to know about the processes of how things are made. But I didn’t study DT beyond Year 9. If you really want to understand the fundamentals of how things work, you can’t beat Physics, Maths, Chemistry and lots of curiosity about everything.
DT is very good for improving your understanding of the many ways we can work with materials to make cool stuff.
while it is it not essential if you want to get into engineering it is a really good start. If you enjoy it, do it.