The key for me is spontaneously reaching out to coworkers who you like. Invite them to parties, or to disc golfing, or a brewery, or whatever fun activity you d

The key for me is spontaneously reaching out to coworkers who you like. Invite them to parties, or to disc golfing, or a brewery, or whatever fun activity you do that needs additional friends. I find that if a coworker comes with me to these activities regularly when we work together, that the activity and the friendship can continue after we no longer work together. You need to develop the out-of-work relationship early and acknowledge that you like each other's company even when you aren't forced to be together. YMMV