Question about understanding irfs in dynare

[jpfeifer]

See

Setting size of stochastic shock

If I understand your question correctly, you are looking for a shock to make a given endogenous variable move by a pre-specified amount. There is no standard routine available for that. If you only have to do this once, I would simply use trial and error. Note that linearization is not recommended. In that case, the model would become symmetric. If you have to do this in an automated way, you could use a solver, but that is quite complicated.