Russian Cyrillic here.

Yes, there are both upper- and lowercase letters. Most kinda look like the same letter.

Yes, there are serif and sans-serif fonts. I haven’t noticed any difference in use between the Russian and the English alphabets in that regard – serif is more prevalent in books and printed media, while sans-serif rules the digital (and maybe headings and headlines in printed).

As for the emphasis, the Russian alphabet and fonts (at least the popular ones) do support emphasis, like bold, italics, etc., but italics is used much less liberally. For example, I often see italics used in English to either make the reader emphasize a word or a phrase differently, or to make a name of a piece of fiction stand out (e.g. Dishonored vs Dishonored). I can’t recall a single time I’ve seen the former being used in Russian, neither in fiction, nor on the Internet – the only thing somewhat close to it would be in-universe letters or writings, but those are often put in their own paragraph with different margins and all.

The italics in the Russian digital fonts is not the same as the Russian or Cyrillic cursive, though. While the latter may be vastly different from the printed letters, varying by the age group (older generations have pretty different cursive from people my age, especially with some letters like the lowercase T), the former is basically the same style shift as in the Latin alphabets. For example:

• Regular: Съешь же ещё этих мягких французских булок, да выпей чаю.
• Italics: Съешь же ещё этих мягких французских булок, да выпей чаю.

As for the Russian cursive, I would say it’s actually closer to the printed Russian than the English cursive is to the printed English. There are some letters that often tend to blend together in cursive, such as the lowercase И, Л, Ш, Щ, but with proper spacing, they’re really easy to tell apart; especially given how they’re not that often that close to each other in most sentences.

The cursive English lowercase F, on the other hand, or uppercase S, or lowercase R, for example, left me guessing the first few times I saw them.

So, the Russian, or the Cyrillic alphabets are pretty boring in that regard when compared to the Latin-based alphabets of Europe. The region may be vast and varied, but its peoples are still pretty close and similar to each other.

Speaking for the Arabic abjad: No, no and we don’t.

Thai does not have upper case letters.

It does have a character that essentially means duplicate the previous word which is a common way to pluralize or emphasize:

Child = เด็ก “dèk”
Children = เด็กเด็ก or เด็กๆ “dèkdèk”

Pretty = งาม “ngaam”
Pretty! = งามงาม or งามๆ “ngaamngaam”

There’s no capitalization in written Chinese.

But there is a “upper case” for writing numbers. Its set of very complex characters meant for writing contracts so you can’t easily tamper with it.

Like “一” (one) could be easily changed to a “十” (ten) with just one stroke, but “壹” also means “one”, but you can’t add strokes to change it, any attempt at tampering with contracts/documents would be easily noticed. Usually this is never used in every-day life.

(Wikipedia https://en.wikipedia.org/wiki/Chinese_numerals#Ordinary_numerals)

It’s not really “capitalization” but more like writing “One Thousand Dollars” instead of “$1000”

Idk what you mean by “emphasis”, but there is no difference between proper nouns and common nouns. I mean, there is italics and bold if written digitally. Or underlining it if written on paper.

(I’m Chinese-American btw)

Hindi or any Indic languages (popular ones) have any case differentiation.

Mostly because emphasis on any word is not literal it is tonal.

So there are these things called - matra (12 matras in hindi)

They are symbols representing inflection/emphasis etc. and we can combine them with each character of the alphabet and convey tone.