They are usually found when googling “steuern “canton” wegleitungen”. For LU I found this general page: Wegleitungen / Merkblätter / Fragebogen / Formulare - Kanton Luzern and directly the page for deductions: https://steuern.lu.ch/-/media/Steuern/Dokumente/Publikationen/2021/Abzge_auf_einen_Blick_2021.pdf?la=de-CH.
When doing taxes with the eTax software or the online version if your canton has one you will see that most deductions are already automatically filled out as those are the same for everyone.
LU doesn’t seem to have an updated 2022 version like my living canton SZ does, not sure why.