The main thrust of this question is covered in an existing FAQ, but the short version is that; (1) Yes, volcanic eruptions can cause global cooling, but (2) many details of the volcanic eruption (e.g., how large is it, where did it occur, what time of year did it occur, where in the ENSO cycle did it occur, etc.) all have substantial impacts on the degree of cooling that will result from a specific eruption, and (3) modelling of the competition between volcanic driven cooling and anthropogenic driven warming suggests given the right details, a large volcanic eruption could pause warming for ~20 years but this would then be followed by ~20 years of accelerated warming (e.g., this paper).

For a deeper dive on all of the above, see the linked FAQ, but it's also worth noting that if we're looking for mitigation strategies for warming, there are probably better ways than hoping for a large volcanic eruption (or other similarly drastic means, like purposefully inducing a nuclear winter). For example, many solar geoengineering proposals, specifically stratopsheric aerosol injection, seek to effectively mimic some of the atmospheric effects of a large volcanic eruption without the eruption.