If you are "lifting" your front end with the adjustable Bilstein 5100's (like the 3rd or 4th clip position) you may need to put the lower shock bolt in and compress the LCA with the floor jack in order to get the upper shock threaded post into the shock tower hole (the spring will need to be compressed more in order to engage the upper shock mount so you can get the rubber/washer/nut on).

Bilstein 5100 Part #: 24-196499 Front shocks: https://amzn.to/3GTqPRU
for this 2019 Toyota 4Runner TRD Off Road
5th generation