Bootloop after installing GApps in Lineage OS
Whenever I used LineageOS 16 I had to use the "other" recommended GApps package by LineageOS.
The so called "MindTheGapps" package.  

See here: https://wiki.lineageos.org/gapps.html  

MindTheGapps link: http://downloads.codefi.re/jdcteam/javelinanddart/gapps
Mirror: http://downloads.codefi.re/jdcteam/javelinanddart/gapps  

I realize they list OpenGApps there as well but for me, only MindTheGapps worked fine.
Ps.: LOS 17 never had this issue on the other hand. The phone I was using is a OnePlus 7 Pro.