Arabic letter ẓāʾ, initial form

No: ﻇ is a fixed initial form of ظ. The letter is called ẓāʾ. Its sound varies across Arabic dialects and can be approximated differently in transliteration; this form adds no new meaning.

Arabic script developed gradually from Nabataean Aramaic. A Nabataeo-Arabic phase belongs to the third–fifth centuries CE, and dated inscriptions with a full Arabic letter repertoire appear in the late fifth century CE. This history describes the development of Arabic writing, not the creation of a separate sign called ﻇ.

Why type ظ instead?

Use ظ for ordinary Arabic text. Arabic letters change shape according to their position in a connected word; writing systems and fonts handle that shaping from the base letter.

ﻇ is a compatibility form for older data. Its “initial” label describes a stored shape, not an instruction to a text shaper, so it may not join as expected. The distinct letter ض (ḍād) can sound close to ظ in some dialects, but the spellings remain different.