I found a pertinent discussion and some helpful links for you.

"What you're talking about are soft endings (-ий) and hard endings (-ый).
With the exception of a handful of words (maybe 40 at the most!) everything else follows the simple rule:
The word gets a hard ending (-ый), except after velars (к г х) and hushes (ш ж щ ч).
Observe: белый, красный, красивый, прелестный, are all hard.
However, далёкий, близкий, больший, горячий, are all soft.

The exceptions are adjectives with soft stems, and they are few (as I said, maybe about 40). They're easy to memorize on their own. They include: синий, последний, etc. "




Here are pages (506 - 510) with ending of adjectives from "Школьный словообразовательный словарь":
Имя прилагательное
https://books.google.com/books?id=1Y...%D0%B9&f=false


Russian Adjectives


https://en.m.wikibooks.org/wiki/Russian/Adjectives


Study Russian Online: Declension of Russian Adjectives
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" ADJECTIVE ENDINGS. THINGS TO CONSIDER

In order to master the adjective endings you need to be aware of the following factors:

A. HARD STEMS

1. Stem stress vs. Ending stress. Hard-stem adjectives can be either

  • stem-stressed (нОв-ый, мАленьк-ий, красИв-ый, хорОш-ий) or
  • ending-stressed (a different ending will show only in masc.sg.: молод-Ой, больш-Ой, как-Ой, голуб-Ой).


2. What consonant does the stem end in:

  • a “good” consonant (нОв-ый, бел-ый, голуб-Ой) or
  • a “trouble” consonant К Г Х Ш Ж Щ Ч (больш-Ой, мАленьк-ий, хорОш-ий).


3. Trouble Consonant Rules:

3.1 7-letter Rule: Never write “ы” after К Г Х ШЖЩЧ: Кы Гы Хы Шы Жы Щы Чы.
Always write “И”: КИ ГИ ХИ ШИ ЖИ ЩИ ЧИ instead.

Alarm spots:

  • Masc. Sg. in stem-stressed adjectives (хорОш-ий, мАленьк-ий)
  • Nom. PL. all stems (хорОш-ие, мАленьк-ие, больш-Ие, плох-Ие, как-Ие)


3.2. 5-letter Rule: Never write unstressed “o” after Ш Ж Ч Щ and Ц.
Always write “е” instead.
Alarm spots:

  • Neut. Sg. in stem-stressed adjectives (хорОш-ее)




B. SOFT STEMS

All soft stems are “good”; they make no troubles, except …
…you have to memorize them.

The only two soft-stem adjectives we are going to have for the time being are:
СИН-ИЙ and ПОСЛЕДН-ИЙ - REMEMBER THEM!!!

Masc. Fem. Neut. Pl.
син-ий син-яя син-ее син-ие
последн-ий последн-яя последн-ее последн-ие"

Pasadena. Ekaterina Schnittke
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http://www.ruslan.co.uk/ruslangrammaradjectives.pdf