How can you use most as an adjective?

No, the Word 'most' is an adjective (many, more, most), a adverb, and an indefinite pronoun.

The indefinite pronoun 'most' takes the place of an unnamed amount that is nearly all, the majority.

The Word 'most' functions as an adjective when it is place before a noun to describe that noun.

The adverb 'most' modifies a verb, an adjective, or another adverb.

Examples:

The player with the most points wins the game. (adjective)

Our room had the most beautiful view. (adverb)

We're expecting a dozen students and most have already arrived. (indefinite pronoun)