There are two possible mechanisms that could explain the position of the adjective in the example sentences that you provided: postpositive adjectives and whiz-deletion.
When you apply an adjective to an indefinite pronoun, the adjective must be placed postpositively (after the indefinite pronoun):
I am looking for something nice - correct
I am looking for nice something - incorrect
Whiz-deletion refers to the removal of a that-is or which is from a sentence:
I am looking for a house that is near to the school - correct
I am looking for a house near to the school - correct
Note that you can't do whiz-deletion if you are left with just one adjective after the that is: the adjective must be moved in front of the noun:
I am looking for a house that is new - correct
I am looking for a house new - incorrect
I am looking for a new house - correct
We always have to go to, you know, someplace nice
someplace is an indefinite article, so this example must use a postpositive adjective: you cannot put nice in front of the indefinite article:
We always have to go to, you know, nice someplace - incorrect
If you were to replace the indefinite pronoun by a noun, the adjective cannot be placed postpositively:
We always have to go to, you know, a place nice - incorrect
We always have to go to, you know, a nice place - correct
You cannot use whiz-deletion to remove that is from the sentence below, because there's only a single adjective after it.
We always have to go to, you know, someplace [that is] nice
Is there any place safe for her?
In this sentence, any is an indefinite pronoun, so a postpositive adjective would have to go after it, and before the noun:
Is there any safe place for her?
This sentence can therefore only be explained by whiz-deletion:
Is there any place [that is] safe for her?
Is there any place safe for her?
Note that, when the adjective is a subject complement, the adjective goes after the noun, though there is normally a verb in between them:
roses are red
the fish smells bad
If the verb is a be-verb and the sentence is converted to a question, the verb is moved to the front of the sentence, resulting in a NOUN + ADJECTIVE sequence:
Are roses red?
One other situation I can think of where you get NOUN + ADJECTIVE is after verbs like
make (CAUSE TO BE),
consider (OPINION),
go (BECOME) and
go (BE) which can take an object followed by an
object complement, which is an adjective.
My five-point plan to make Britain safe again - Daily Telegraph
North Korea suggested today that it did not consider negotiations finished. - New York Times
Why Things Always Go Wrong - entrepreneur
6 reasons why people go hungry - global citizen