There are many things you are asking about in your post, but it is unclear what the actual question you want answered is.
Have you tried chaning the text weight? Alternatively, strong emphasis. Note that you’ll have to make sure the font you use supports changing the weight.
Are you asking how you can change the font? You gave an example on how to do that in your post
Yes it does?
#set text(font: "Linux Libertine")
the grey fox jumps over the lazy dog \
THE GREY FOX JUMPS OVER THE LAZY DOG
The included text looks to be a citation. Is there a particular reason you are typing it manually, instead of referencing a bibliography? Are you possibly asking how you can make the citation keys be bolded automatically?
Why not use smallcaps with Linux Libertine instead of Linux Libertine Capitals, which is just a subset of the same font (from what I could tell)? If it is indeed an issue with the font you’ve installed, using the standard font instead of a subset is more likely to include all the necessary features.
#set text(font: "Linux Libertine")
#smallcaps[*the grey fox jumps over the lazy dog*] \
#smallcaps[*THE GREY FOX JUMPS OVER THE LAZY DOG*]
At first: at the beginning I set Linux Libertine as default font. But after a while, when I looked for a nicer font I found Libertinus Serif better, but without Capitals.
Second: Yes I tried weight for Linux Libertine Capitals. Typst gives an issue for “Linux Libertine Capitals Bold”, I modified also some around with no effects. - Your proposal: it doesn’t look like Capitals and before I have to rewrite the Text from Dörfel to DÖRFELT
Third: yes its a reference to a manually created Biography. It is made from the author. To put it into Zotero or other bibs its a lot of work. And in my situation a reference to bibliograph produced digits, surrounded by a square. The solution for this I´ll try later. This is my first serious attempt using Typst to help a non-profit association.
It’s probably best to continue working as before. Thanks for your answer.
I tried it and using weight: "bold",strong[your text] or *your text* works. You have set the font to “Linux Libertine Capitals” and have “Linux Libertine Capitals Bold” installed, then Typst uses the bold style from it.
#text(font:"Linux Libertine Capitals", fallback: false, 11pt)[*Dörfelt et al.* (2002)]