2B and 2C (+1 on block) are his main safe pressure reset tools. The former is negative on block but it works as one because Ragna has many options after 2B, so, you're conditioned to block anything after 2B. It can easily get beaten by fast 5B's and A's, just look out for it. 2C works the same way and his options are safer but more limited. Most Ragnas go for 2C> 5B or 2A to reset pressure, it can be beaten by reversals or fast 2A's, and 2C> 5C or 2D to keep you in check from mashing (these are frametraps).
These are his safe pressure resets. Unsafe ones are moves like BS (+5 on block but slow), DS (slow startup, can be jumped out), 6D (slow startup, 5A's beat it).
Ragna loses many options when he's outside of 2C and 5B effective ranges, so, you can either expect something like "5C> GH or 5C> 5D> Special cancel" for him to keep up the pressure. Anything he does at that point to maintain pressure will be mostly unsafe, so always expect for something like GH, DS, BS... or HF. And always block high and prepared to counter something whenever he does 5D.