are these sentences correct?

[Allthewayanime]

I'd like to know if these sentences are correct:

Let's look at its inside.
Let's look inside

[Dozy]

They are both correct English, but the meaning is not identical. The first sentence has a stronger sense that the thing itself has inner parts, or inner components, as opposed to simply being a container for something else. The second sentence is more common.

[Allthewayanime]

Wouldn't be in the first sentence 'insides' instead of 'inside'?

[Dozy]

"insides" is also possible. If anything, "insides" has even more of a sense that there are internal workings, such as a mechanical or biological parts.