No — and it is worth understanding why, because both feel like they should help and both usually make the result worse.
TikTok's playback ceiling is 1080p for the overwhelming majority of uploads. Send 3840×2160 and the platform downscales it on the way in, then compresses the result like any other file.
That downscale is not free. Scaling a large frame down quickly leaves aliasing and mush in detailed areas — grass, foliage, fabrics, fine text — and the artifact is baked in before the video is even encoded. Starting at 1080p avoids the whole step: nothing has to be resized, so nothing gets damaged by resizing.
The instinct that "more pixels is safer" is the opposite of what this pipeline rewards.
Same shape of problem. TikTok tops out at 60fps, so a 120fps file has to be retimed — frames are dropped to halve the cadence. Depending on the file, that can read as slight stutter, or as motion that looks subtly wrong, and it costs you detail for the privilege.
There is no setting on TikTok that rewards 120fps. Shoot 120 if you want the option to slow footage down in the edit — but the export going to TikTok should be 60.
For an upload you intend to look its best on the platform:
Those five numbers beat a 4K 120fps upload in practice, every time, on this platform.
You do not need to reshoot. Export a new 1080p 60fps constant version from your 4K or 120fps master. That is a re-export, not a downgrade — you are choosing the resolution TikTok would have chosen anyway, and doing it with better control than their automatic downscale gives you.
Two things to get right when you do: set the export frame rate explicitly to 60 and constant, and keep the bitrate high. A 4K master downscaled on your own machine at a generous bitrate will hold up far better than the same master downscaled on theirs.
Keep the 4K and 120fps masters. They are worth archiving, and they matter if you post the same footage to platforms that do serve higher resolutions, or if you want to slow 120fps footage to 30 for a smooth slow-motion shot. Just do not send them to TikTok as the upload file.
Not on playback for the overwhelming majority of uploads — the ceiling is 1080p, so a 4K file is downscaled on arrival. That downscale can introduce more visible artifacts than uploading 1080p in the first place.
No. TikTok caps at 60fps, so 120fps footage gets retimed and you lose detail for no benefit. Shoot 120 if you want slow-motion options, but export 60.
Practically, no. It adds a downscale step that can soften fine detail. 1080p with a high bitrate and a constant frame rate is the combination that looks sharp.
Yes — re-export at 1080p, 60fps, constant frame rate, with a high bitrate. That gives you the resolution TikTok wants with more control than its automatic downscale.