The Torah says that we must give a poor person all that he lacks [דֵּ֚י מַחְסֹר֔וֹ אֲשֶׁ֥ר יֶחְסַ֖ר לֽוֹ.] [Deut. 15:7-8]
The Shulḥan Arukh interprets:
How much should be given to the poor? Dei machsoro asher yechsar lo ... All that he lacks... How is that? ... Even if he was used to riding on a horse with a servant running ahead of him while he was rich, and now he is poor, buy him the horse and the servant -- each man according to his needs... If he came to get married, rent a house for him, prepare a bed for him and house utensils, and find him a wife. [Shulḥan Arukh, Yoreh Deah, 250:1]
I would like some sources that elaborate on that. What if he is a king in exile: Are you supposed to support him in regal style? What if you yourself lack what he is accustomed to? I know that Hillel did that [Ketubot 67b] and that he might die if you don't [Ketubot 67b]. Are there recent cases where this was done?