[ang_cire]

No, but languages that use glyphs that are monophonemic and non-phonetic (one-sound per-glyph/character) don't have contractions, which are a function of removing some component part of a word when combining them.

For instance, both Chinese and Japanese use kanji/hanzi, but Chinese is monophonemic, and does not have a phonetic alphabet that characters can be broken into (radicals aside, which are not related to sound). Japanese does (kana).

As a result, combining 2 characters in Chinese never changes the sound of some sub-portion of a character; it's either the whole sound that changes, or nothing. In Japanese, on the other hand, individual kana within a character can change (e.g. Rendaku), so for instance 'hito' (person) put twice in a row becomes hitobito instead of hitohito, because hito is comprised of 2 kana characters: 'hi' and 'to', and 'hi' becomes 'bi'.

Emoji have no subcomponent characters, so you either would need an emoji for a contraction word in addition to the source words, or, more realistically, you just wouldn't have them at all.

[thfuran]

And you're saying that in Japanese and Chinese no word is ever informally pronounced in abbreviated fashion by eliding some phoneme(s)?

[ang_cire]

In Japanese, yes, because it has a phonetic alphabet. For example, "konnichiwa" is often shortened as "kon'chiwa".

In Chinese, there is shorthand slang, but not shortening of words in writing based on spoken sounds (since it's not phonetic).

So even if "wo shi" (I am) might be spoken more quickly, there's no way to write that shortened version out in Chinese. You will actually see Chinese speakers use Latin characters and Arabic numerals for phonetic shorthand, (e.g. '88' for "bye bye", because 8 is pronounced 'ba'/'bai'.