Elevated cortisol levels are part of the bodies adaption to stress. Usually highest in the morning rather than afternoon, except for maybe if your body clock is shifted like it was in me. That might cause the rise later than normal.
The Kidney energy Chi/Qi affects cortisol. Treating/supporting the kidney can lower cortisol to more normal levels. As the kidney energy becomes weak, cortisol levels rise until adrenal failure. This all shows in the iris of the eye. Background cortisol levels rise as a person ages for this reason, mostly because of a faulty belief system involving fear of expressing emotion which causes significant levels of unnecessary emotional stress. Anger and loss should not be stressful if the emotions are handled correctly. Unfortunately most parents get this very wrong and teach their children to be stressed when experiencing emotions.
The best thing for the kidney in TCM is Tu Si zi (dodder seed) to which Gou Qi Zi (Wolfberry or corrupted to Goji berry) is often added.
Glycine would calm the mind by raising GABA. I doubt that it will make a large difference on cortisol, only lowering it a bit, especially with anxiety states. PhosphatidylSerine is meant to lower cortisol but I would not use that as it is not supporting the reason for the high cortisol. Cortisol serves a purpose so lowering it is not really beneficial unless the cause is addressed. There is research which suggests that PS does lower/attenuate cortisol release.
I use Tu Si Zi/Gou Qi Zi myself and know how effective it is in lowering cortisol. I have had a synacthen test for adrenal function which showed quite high levels after I abruptly stopped Tu Si Zi. Tu Si Zi is eliminated after about 16 hours max and is needed at least every 12 hours. I can feel the effects of high cortisol when I do not take Tu Si Zi. Be aware that Tu Si Zi does have other effects including increasing the weight and function of the pituitary gland which is also helpful to me. Supporting the HPA axis and might have some affect against some cancers.