Is the word necessário the same in Brazilian and European Portuguese?

Yes

The meaning, spelling, and grammatical functions of "necessário" are identical in both Brazilian and Continental Portuguese. The only difference is pronunciation.

In Brazilian Portuguese, vowels are generally more open and clearly articulated. The unstressed "e" at the beginning of the word is clearly pronounced as a distinct syllable.

In Continental Portuguese, the language is more "stress-timed," which leads to significant vowel reduction. The unstressed "e" is often swallowed or reduced to a very short, nearly silent sound (a schwa-like sound), making the word sound closer to "n'cessário."

Brazilian Portuguese Examples

1. É necessário levar o guarda-chuva. (It is necessary to take the umbrella.)
2. Não é necessário fazer isso agora. (It is not necessary to do this now.)
3. Tudo o que é necessário foi entregue. (Everything that is necessary was delivered.)
4. É necessário ter paciência com crianças. (It is necessary to have patience with children.)
5. Você viu se é necessário comprar pão? (Did you see if it is necessary to buy bread?)

Continental Portuguese Examples

1. É necessário levar o guarda-chuva. (It is necessary to take the umbrella.)
2. Não é preciso fazer isso agora. (It is not necessary/needed to do this now.)
3. Tudo o que era necessário foi entregue. (Everything that was necessary was delivered.)
4. É necessário ter paciência com as crianças. (It is necessary to have patience with the children.)
5. Viste se é necessário comprar pão? (Did you see if it is necessary to buy bread?)