Using 'sat' and 'stood' as adjectives

An intransitive verb is one that cannot take a direct object. Normally, intransitive verbs cannot be made passive.

The past participle is normally passive (except with have).

From this it follows that intransitive verbs, like sit and stand in the senses intended, normally cannot have past participles without have.

However, there are some intransitive verbs that are best considered idiomatic exceptions: they can still have past participles. You could say those exceptional past participles don't have the normal passive sense. You might call them adjectivised, but I'm not sure I'd pick that term, considering that sat and stood cannot be used attributively (before the noun).

I am sat here.

She was stood there.

We are agreed.

She was gone.

There are more.