>>153873technically, yes, but there are a lot of publications that by "radical" mean "basic codified grapheme"
in the context of this conversation, 曾 was originally a visual representation of a basket, as you can see
here and
here, showing a square body with two straps, but this was later segmented and simplified and nowadays 曽 looks closer to 日+田, it would not be unreasonable to call them its radicals
indeed if you look at
kanjipedia's entry, its 部首 is said to be 曰 (not 日), even though this is also ultimately ahistorical and not particularly useful today, humanum is more accurate in listing 曾 as itself being its sole unique component, but you're not going to find it as such in any kangxi-based dictionary