Presuming you mean in the verb:
sagon "to be" is irregular:
sagon "to be"
- 1s (I am) iksan
- 2s (you are) iksā
- 3s (he/she/it is) issa
- 1pl (we are) iksi
- 2pl (you are) iksāt
- 3pl (they are) issi
For most other verbs, talking only about the present indicative:
For the verb form, in general, the 3rd person plural (they) is more likely to have an s or z (often an s) in the last couple of letters (the other letter is likely to be an i) than the 1st person plural (we).
Examples of the 1st person plural (we):
jaeli, epi, sēni, derēbi, pāsi, verdi, morghūli,
Examples of the 3rd person plural (they):
jaelzi, epsi, (epis), sēnzi, (sēzi), sēnis, (derēbzi), derēbis, pāsis, verdis, morghūlis
Source and more details: https://wiki.dothraki.org/High_Valyrian_Verb_Conjugation#Indicative
Against the general remark about an s being found in the last couple of letters for the 3rd person plural, notice that pāsagon, because of the -s- in the stem, has the "we" form of pāsi. Which can make it and some other similar verbs look like the "they" form when they are in the "we" form. This means that to distinguish the "they" form, an extra -s must be added: pāsis.
There may be other complexities - my remarks here are only intended in general.