Physical exercise after work, cut out screen time a couple hours before you want to sleep (especially engaging screen time), consider cutting off caffeine earlier in the day (or totally for a while and ease back in), get treated for anxiety (not necessarily medication, therapy techniques like CBT can help in a wide variety of areas).

The biggest one for me was physical exercise. Working out hard for 1-3 hours after work (most people can't put in 3 hours, I know) left me sufficiently physically exhausted that whatever mentally engaging activities I got into later, I was crashing by midnight no matter what. Doing this after work was also critical as it helped create a clean break from work (where many stressful or technically engaging thoughts come from for me). Exercising in the morning did not have the same effect.