What about 'My bag is red'? 'My red bag' is not a complete sentence in English.
Tas saya merah = My bag is red
It could be though. "Which bag did you want to take on holiday?" "My red bag."
There is another question that translates "Topi saya merah" into only "My red hat". I was wondering if there's a difference when the pronoun comes after the whole noun phrase vs just after the head noun.