If you want small caps best not to rely on CSS font-variant but instead make a subset font of proper small caps (you can use Font Squirrel with a font that has small caps) and embed it. These can be keyed to capitals rather than lowercase so you still get caps if the device doesn't use the embedded font.
But small caps are too regularly aligned for a telegram. Why not use an actual telegram font? For example:
https://www.fontspace.com/category/telegram