I am not a psychologist either, but, firstly, I am actively working on my psychological state, and secondly, I read books on psychology.
I will list here 2 ways to relieve stress.
The first is meditation. If done correctly, it is very effective. Enough 10 minutes. The main thing is not to try to control thoughts, but simply to observe them, let them come and go on their own. If you know English, I recommend the Headspace app for your smartphone. If you do not know, then look for information on your own on the Internet about how to do meditation.
The second method is based on the statement that emotional stress is a consequence of cognitive conflict. If this is a serious conflict, then you need to try to resolve it purposefully. For example, someone was rude to you, and you cannot accept it. You have to try to do something to yourself. For example, you can take a compassionate stance by telling yourself that the person probably has serious mental problems if they are rude and calm down. I think the combination of the two approaches gives an even better result. I hope you find this information useful. Good luck!
Not a psychologist, but let me list the effective, harmless ways:
Square breathing: when you breathe for 3-5 minutes according to the scheme "inhale - hold - exhale - hold" mentally counting on each stage up to 4x. The plus is that you can use it when you need it.
Yoga nidra (mental sleep session) - usually after yoga, some instructors arrange a 10-15 minute session, or you can find audio versions on the Internet
Meditation - gives you the ability, prudence and concentration of attention, and for a start, 5-10 minutes a day is enough
Also doing sports: yoga, running, workout
in the end, just to breathe and do some resource work that gives you joy - drink your favorite tea / coffee, take a walk, listen to your favorite music, call your friends or watch a comedy, etc.