You want to use a thesaurus, and you've made an erroneous assumption in the body of your question:
For example "very small" → "negligible". Of course the correct substitution depends on the context.
My point is, where can I find a list of appropriate words?
Searching for "synonimous [sic] small" for example does not work, because I want the "very" to be emphasized.
Actually, looking at a thesaurus will work, because many synonyms listed for "bland" words will often emphasize the "very" part.
For example Collins has a thesaurus; looking under small shows quite a few words that connote "very small," including the one you list:
little, minute, tiny, slight, mini, miniature, minuscule, diminutive, petite, teeny, puny
unimportant, minor, trivial, insignificant, little, lesser, petty, trifling, negligible
The same goes for the synonyms of big; many of these mean "very big" – either in size, or in importance:
large, great, huge, giant, massive, vast, enormous, considerable, substantial, extensive, immense, spacious, gigantic, monumental, mammoth, bulky, burly, colossal
important, serious, significant, grave, urgent, paramount
and most of the synonyms for cold seem to mean "very cold":
chilly, biting, freezing, bitter, raw, harsh, bleak, arctic, icy, frosty, wintry, frigid
So, open up that thesaurus! I'm sure you'll find that
very big book to be very helpful enormous tome to be beneficial.