Does promoting videos work?

Only if the video is good and you target the right audience. who is the right audience? you will only know with trial and error. if your video has high retention rate and high likes ratio, promotion to the right audience will 100% work. do no promote videos with less than 15% watch rate per 10 seconds. (7.5% per 20 seconds)

If you try promotion. use the minimum amounts to test results and do no let tiktok choose audience for you. and if you plan to use promotion to go viral so then you will have much more regular views, forget about it. once the promotion will end, your traffic will go back to normal, but ofc the followers will remain. if you try to grow a channel, do not use anything but "more views".