Earlier quoted context omitted.
Probably by choosing Transcoding: Direct Play in the admin account settings options for the Server. https://jellyfin.org/docs/general/server/transcoding/ I recently setup Jellyfin pretty thoroughly on a small form media centre with 4 x 2TB SSD drives for the media and went through all of this for direct to TV, via client to iPhones and to an XBox etc. I passed that on three weeks back to a son for his household so I…
Your first link is a not a list of settings, it's an explanation. You can disable transcoding for a specific device (or user). However, it just means that the client will not show some videos, even though it can play them in reality. This is determined by the device profile shipped with the DLNA plugin (!). You used to be able to replace that, but that broke for me with the recent changes wrt DLNA. I don’t even mind…
The Jellyfin documentation is poor and lags. I would screen shot what I worked out for myself but that ship's sailed and moved on. I did have to tweak some profiles but ultimately I got all media playing on pass through with no transcoding so it is doable.
My apologies for not being in a position to cough up details, that was my second pass through Jellyfin, I now like it much better than I did the first time through. If I set up a third instance for someone else I'll take to the time make notes and maybe feed them back into the community docs (if they're relatively easy to update).