So I recently found out you can say things like "Mi malsatas" to mean "Mi estas malsata."
Can you do this with any word? If not, how do you know when you can or can't do it.

Mi ruzas = Mi estas ruza?
Mi grandas = Mi estas granda?
Mi rapidas = Mi estas rapida?

In principle one can do that with any attribute, that does not alreay have as a verb. E.g. in the case of "morta", "morti" already has a meaning different from "esti morta".

"rapidi" is also not "esti rapida".

PIV:*rapid/a
1 Faranta grandan vojon, grandan laboron aŭ alian agon, en mallonga tempo: li estis rapida kiel fulmo, kiel aglo, kiel sago; rapida kuriero, ĉevalo B, ŝipo Z, trajno; rapida fluo, vento; la rapida plumo de bona skribisto B. ☞ diligenta.
2 Farata aŭ okazanta en nur mallonga tempo: rapida movo, flugo, laboro; rapida decido, progreso, resaniĝo; tro rapida faro estas nur baro Z; tro rapida riĉiĝo Z, edziĝo Z.
rapidi (ntr)
1 Peni atingi lokon en mallonga tempo: ŝi volis rapidi hejmen Z; la infanoj rapidas al la lernejo Z; ili rapidis returne al siaj lokoj X; rapidi al stacidomoB; li rapidis en la tendonX. ☞ flugi, galopi, kuri.
2 Peni plenumi agon en mallonga tempo: manĝu ĝin rapidante; ĝi estas Pasko de la Eternulo X; ŝi rapidis reveniZ, transkuri la straton Z; piedoj, kiuj rapidas kuri al malbono X; kiu rapidas riĉiĝi, tiu ne restos sen puno X. ☞ urĝiĝi.
3 Fari agon sen atendo, pli frue ol normale: ne rapidu insulti, volu aŭskultiZ; ne rapidu koleri Z; ne rapidu kun vortoj, rapidu kun faroj Z; ne rapidu, trankvile decidu Z; sentante min jam tute bone, mi rapidas skribi pli detaleZ. ☞ hasti.

Forming a verb out of word that in the dictionary is listed an adjective presents the idea in a verbal light. The question then arises as to whether in the real world there is an action which may be appropriately so labelled.

Rapidi becomes hurry, speed, hasten rather than meaning to be characterised as quick.

An express train is a rapida trajno even when stationary, but it rapidas only when moving.

On the other hand if I say a plank of wood larĝas je 10 cm, I mean that it is 10 cm wide. There is no real world action for the plank of wood to perform other than that of being wide, or being characterised by a certain width.

sudanglo:Forming a verb out of word that in the dictionary is listed an adjective presents the idea in a verbal light. The question then arises as to whether in the real world there is an action which may be appropriately so labelled.

Rapidi becomes hurry, speed, hasten rather than meaning to be characterised as quick.

An express train is a rapida trajno even when stationary, but it rapidas only when moving.

On the other hand if I say a plank of word larĝas je 10 cm, I mean that it is 10 cm wide. There is no real world action for the plank of wood to perform other than than being wide, or being characterised by a certain width.

Yes.
"ruzi" also in not "esti ruza", but "agi per ruzo", act with guile

tio tias tiel!

gxiskiamas la senkunvojagxo pro kverele?
kienis la vojagxo ef kverele?

mi jam prezentis iel tian temon cxe forumo "konsultejo" per mesagxo "kien kial kverelo?". pliprecize, tiea tio priis rilaton inter relativo kaj prepozicio (cxu cxiu relativvorto sias prepozicion?).

amigueo:
mi jam prezentis iel tian temon cxe forumo "konsultejo" per mesagxo "kien kial kverelo?". pliprecize, tiea tio priis rilaton inter relativo kaj prepozicio (cxu cxiu relativvorto sias prepozicion?).

Vi tedis cxiujn per fireklamo de via fadeno! Neniu komprenas vian "kien kial kverelo?". Krom tie, cxi tie oni skribas angle.
You have bowered evrebody by your thread. Nobody understand your "kien kial kverelo?". Moreover, they write English here.

sergejm:Nobody understand your "kien kial kverelo?". Moreover, they write English here.

pardon, it was an error!

"kien kial kverelo?" (summary):
husband and wife were planning together a together travel (kunedzoj kunplanis kunvojagxon). they were not agree about where to go (ili ne interkonsentis pri kieno). that disagreement made them querel (seninterkonsento kialis kverelon). a friend of the couple wonders why they quereled (kial kverele?). concisely, they quereled about/because of the travel destination (kien kial kverele). but, what destination made them querel? ("kien kial kverele?" aux "kienus la vojagxo?"). it is known, it is not a secret, fortunately: they quereled about travelling to New York (vojagxo novjorkenus kial kverele!).

that small story intends to make us think about the possibilities of the relative words in esperanto, and about the relationship between the relative word and its quasi equivalent preposition. secundarily, "kienus", "kialis", "sias", "efas", they have to do with this theme tread.

vojagxa novjorkeno efas kverelon (ef|kial).

"ef", not official esperanto preposition, meaning "with the result being..."

of course, these considerations are to receive commentaries from advanced esperanto speakers.
pardon, again

amigueo:
husband and wife were planning together a together travel (kunedzoj kunplanis kunvojagxon).

Husband and wife would be "geedzoj." "Kunedzoj" (together-husbands) would probably be understood as a gay couple.

sergejm:
You have bowered evrebody by your thread. Nobody understand your "kien kial kverelo?". Moreover, they write English here.

Please explain what you mean by "bowered".