Need advice for stress management strategies

Find a quite place. Use some guided meditation (an app like Insight Timer is great and free). For immediate relief try some deep breathing exercises which can be done at your desk.

Meditation breaks, if you're doing the junk food eating at work. Just taking 1-2 minutes to relax, breath deeply/slowly, pay attention to how the breathing feels, a few times a day - that can help.

If you can walk occasionally, that may help - some people take their bathroom break at a more distant restroom in their workplace, just to get some steps in.

Stretch: You can do this seated, while doing some work tasks, even. Stretch out one leg at a time to feel the stretch, rotate the ankle and knee; put your hand behind your neck and use the opposite hand to gently push downward on the elbow to gently stretch your shoulders; do neck stretches to front, sides; etc. Do a web search for "desk stretches".

Prepare yourself by bringing more nutrition-dense snacks to work, then nosh on those instead of whatever you're eating now. Even salty things like crispy chickpeas or dry-roasted soybeans are more nutrient-dense for the calories than potato or corn chips. Even sweet things like fruit are more nutrient-dense than candy bars. (Dried fruit is good, but easy to over-eat. When I use dried fruit as a snack, I sip water alongside, take small bites, and chew it thoroughly, which helps it be more quickly sating.) If part of your junk food intake is sweet drinks, consider flavored sparkling water, zero-calorie soda/pop, herb tea (cold or hot), coffee with reduced-calorie flavored syrups, or something like that.)

I hear you! Gaining tools to deal with stress is very important. A lot of it for me, has been experimenting with what works and doesn't. Sometimes what works will be situational, so learning to be flexible and adaptable is very key. Finally, I would say that sometimes feeling the stress rather than always running from it is good practice. I say this because running away or avoiding a difficult thing all the time has created more problems for me than it has solved.

As a fast way to destress just find a quiet place. Close your eyes breath in for 7 seconds and breath out for 11 seconds. Do this for 3 to 4 minutes a few times a day. It really reduces your blood pressure. Watch it on your fit bit and see it come down.
I do that breathing/ counting exercise sometimes if I wake with anxiety as well.
At lunchtime get out for a walk studies show that it makes you a more productive employee in the afternoon than sitting at your desk eating lunch and continuing to work and get more stressed.

I'm all about walking for stress relief. No music, no audio books, no podcasts. Just quiet time to process.

A critical task list was essential for me reducing my stress (personal and professional). If work was getting bad, at the end of the day I would take 5-10 minutes and write down 3-5 critical things I needed to do the next day. Limit the list to no more than 5, and be specific - if you need time to clean up an inbox, set a time limit and a timer.

I also sit down every morning at home and write a "personal" critical task list for that day, making sure at least 2/3 of the items are touches on my bigger goals (ideally all of them are towards those bigger goals, but some days there's just other stuff that needs to get done).

They don't need to be big things, and once I complete the list I have "won" that day. If there is more time, then I can move on to other items, but I know the most important things were touched/handled/moved in the right direction.

Probably doesn't work for everyone, but it has literally transformed my life the past 9 months.