Thanks for the images. It is not clear to me this is indeed Rhinocerous beetle damage. Usually we see the v-shaped hole. But since these are very young plants then maybe such holes do not appear.

Have you seen any adults?

Let us assume this is Rhinoceros beetle damage. Below is some advice. The promotion of natural enemies is a very good approach that reduces the incidence, is cost effective and does not harm your health like pesticides can. As with any pest insect we must think about the conditions now and what the conditions will be in the future. So, make sure you create the worst conditions for this insect so they dont keep breeding and cause more damage.


"Rhinoceros beetles can be controlled by eliminating the places where they breed and by manually destroying adults
and immatures.
• Chop and burn decaying logs or break them up and destroy any
rhinoceros beetles developing inside.
• Cut stumps as close to the soil surface as possible.
• Dead, standing coconuts should be felled, chopped, dried, and
burned.
• Rhinoceros beetles do not usually lay eggs in potential breeding sites that are obscured by growing vegetation. Vines or
ground covers can be planted or allowed to grow over logs or
stumps that cannot be destroyed.
• Piles of dead leaves or grass can be composted, used for mulch,
burned, or spread on the ground in a thin layer.
• Compost piles should be maintained properly. When turning
compost piles or applying compost to plants, destroy any rhinoceros beetles found. It takes longer for rhinoceros beetle larvae to develop than it takes to make compost, so properly maintained compost should not serve as a source of rhinoceros
beetles.
• A hooked wire can be used to extract and destroy rhinoceros
beetle adults feeding in palm crowns.
In many countries, the fungus Metarhizium anisopliae or the Oryctes virus are used to control the rhinoceros beetle. More recently a
chemical attractant, ethyl-4-methyloctanoate, has been used in traps to attract and kill the beetles. Both Metarhizium anisopliae and
the Oryctes virus are present and helping to reduce rhinoceros beetle populations"

https://www.ctahr.hawaii.edu/adap/ASC...