As I understand it, Latin isn’t supposed to have relative adjectives. Where it appears they might exist (e.g. Dido: urbem quam statuo vestra est Aen. 1.573,), other explanations are sometimes offered (e.g. attraction).
However, Pinkster speaks of the “so-called adjectival” use of the relative and provides as an example this:
Quibus est dictis dignus, usque oneremus ambo.
(‘Let’s both give him a good load of the language he deserves!’, Pl. Mer. 978)
https://www.harmpinkster.nl/files/articles/Relative_clauses_in_Latin(2012).pdf
His use of “so-called” may intend to indicate that he doesn’t accept the concept of an adjectival relative, but I think it is just rather than he prefers to use “determiner” rather than “adjective.” Besides, later on he lists the relative under “substantival/adjectival”:
substantival/adjectival:
qui ‘who’, ‘that’, quisque ‘whoever’, ‘whatever’, quisquis ‘whoever’, ‘whatever’ (all from
Early Latin onwards)
Furthermore, Maclardy, in reference to quem si fata virum servant in 1.546, says: “… qui, quae, quod, which may be pronoun or adjective” (Maclardy, The Aeneid of Virgil, p. 230; incidentally he explains urbem quam as attraction).
So, can we say that Latin does have an adjectival use of the relative? Thoughts?