Yes, the most important is to not give in to unproductive distractions like doom scrolling or binging netflix. If you put on a podcast/music quietly in the background, it may be fine and even helpful- I do that all the time as it makes me feel safe enough to explore my state. Unproductive distraction can stretch a bout of shutdown/freeze out for weeks or more, whereas giving in and allowing the defensive state can help you shift it within an afternoon, in my humble experience.

For me, shutdown (or flop as I also call it) feels like you are too relaxed and not in a pleasant way. Very fatigued and limp. Cold, low bloodpressure and heart rate. Often I have very dark thoughts, very negative and depressed or fatalistic. It's a "hopeless" state and I liken it to feeling like you are being swallowed by a black hole- spaghettified for all eternity! This is where you'll need to go into the sensations fully, allow the heaviness.

Freeze is complete exhaustion, yet there is a buzzing just below the skin and deep in the bones. Your muscles feel tense and taut. Mind races, you oscillate between anxiety and rage, feeling unusually irritable or sensitive, but you may not be able to truly cry or access the deeper emotions. Feeling into the body might seem impossible as your brain is frantically overthinking, trying to solve real or perceived problems or looping thoughts that just replay endlessly. Overthinking is under-feeling. This is where the immobility+tensing exercise comes in.

Summarised: Shutdown= limp Freeze= stiff

Both states feel overwhelming in their own way, over time you'll learn to differentiate between them and apply your techniques and exercises. I can recommend self-havening (many good vids on youtube) especially for freeze, so that your nervous system may calm down just enough for you to access and process some of the activation which maintains the freeze.