Expressão da Série "Lupin'' (Netflix): Send for

send for someone/something
— phrasal verb with send verb [ T ]
Us
/send/
Past tense and past participle sent us/sent/
To request or demand that someone or something come:
Once he was settled in America, he sent for his wife.

From Cambridge Dictionary

Sugestão:
"Você pode me deter. Mandarei chamar meus advogados. Você será demitido em 15 minutos."

Thank you.

Pode usar "fetch" no lugar de "send for"? O que eu uso no lugar de "send for"?

Hi!
Você poderia usar “request” ou “demand the presence” ao invés de “send for”.
“Fetch” seria buscar ou trazer, não seria, portanto, adequado no contexto, exceto se você mandar alguém ir buscar pra você, já que está detido. Mas, o “send for” dá mais um sentido de propósito ou finalidade. É o mais coerente com a frase apresentada.

Fetch has a ring of "trazer/buscar", whereas "send for" adds a shade of meaning here.
First thing, before I explain "send for": as Cinnamon has pointed out if we change the sentence to "I will fetch" it will suggest that "vou buscar".

With "I will send for (someone) it will mean "vou mandar buscar/vou (mandar) chamar/vou mandar vir/chamarei... (alguém, que no caso são os advogados).

At this juncture, you might have concluded that usually someone in power/superior people are the ones that "send for" inferior people, or subordinates, etc. In some cases we can change that 'in power' for 'powerful" (moneyed people, etc).
Summing it up, "I'll send for my lawyers" suggests something that if you are not powerful (enough) or moneyed, etc, it will come off a threat, or that you are arrogant or somehow noncollaborative. It will work against you then.