The air will often come out at the stem because the tape seals the rest of the tire pretty well. I patch my Tubulars but others have used
https://www.tirealert.com/
IME, sealant doesn't work as well as a patch. I have used it on the road or before a $$$ century length event but not on a leak discovered at home.
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I don't do: disks, tubeless, e-shifting, or bead head nymphs.