I have just learned to capitalize "Chapter" and "Section" when referring to specific chapters or sections.
Is this also the case for "Ref." as in
"As shown in Ref. [12], ..." or
"The authors of Refs. [1-3] conclude that, ..."?
I have seen this in an peer-reviewed journal and think that it looks good but somehow I can't find an objective reason to capitalize it. I don't want to trust my feelings since my mother tounge is German.
Context: I am writing my master's thesis right now.
As I argued in this answer, better not to use "Ref." in front of numerical citations with brackets unless a publisher requires you to do so to conform to their style (but as I say in that answer other users will likely argue the opposite). In any case, if you fail to conform to a publisher's style, the copy editor will likely fix it (not a certainty).
Also the capitalization typically depends on the publisher: some publishers write "section", "chapter" etc. with a lower-case initial, others with an upper-case one. Personally, I prefer lower case ones.
If for your thesis you don't have to follow a specific university guideline, or the advisor's advice (did you ask?), make your choice according to your preference, but be consistent: if you write "Sec.", use the same capitalization also for "Ref.". And if you write "Ref." abbreviated, don't write "Section" in full.
It depends on your intended audience. These things are not cast in stone. They vary from one place to another, even over time. A new editor at a journal may want his own way.
This is by no means the only formatting thing you should be thinking about. Lots of things will cause an editor (or equivalent) to grow distended veins in his forehead because you did it one way, while the next institution over will develop apoplexy because you did it the other way.
Check what the preferred style is where you hope to publish. For example, if you want to publish in journal X-Y-Z, go get a few copies of that journal and see how the articles in it do this. Then copy it. Or if it's a book or conference proceedings, check with the publisher or editor.
For a thesis, check with your department/faculty etc., for what their style guides are.
Some other things you may want to think about. There are lots more.
Some doc-prep systems will let you reformat such things very simply. The system LaTeX for example lets you use a specified style. You type in \cite{citedPubName} in your text. (Or something like that.) Then you specify the style file to include, and it prints out your document with the style indicated. If you, or your publisher, want to change some part of the style, you change what style file you use. Many journals will even supply you with the style file to use to be compliant with their requirements.
Plus, many journals will accept LaTeX directly, and format it as they need for publication.
I would suggest not. But, you can pretty much do as you please and if there is no pushback then you are fine. An editor of a journal might have a preference, however, which you need to honor. Likewise an advisor. Relax.
