=Comparatives and Superlatives=
Two-syllable adjectives can form the comparative by adding -er, like one-syllable adjectives, or by putting more in front of the adjective, as with three-syllables. Similarly, these adjectives can form the superlative by adding the ending -est or by putting most in front of the adjective.
Some adjectives, however, do not have a different form for the comparative or the superlative, and you must use ‘more’ and ‘most’ to form them. In general they are adjectives that have more than two syllables or end in ‘ful’, ‘ing’, ‘ous’, ‘ive’, ‘ish’, ‘al’, ‘able’ and ‘ed’.
Examples
Superlativos
Comparativos
If you are interested in understanding the subject better, visit the following pages:
https://www.ingles-practico.com/basico/comparaciones-I.html