Pretty good summary of the current thinking on the R0 value we're seeing for SARS2. Early estimates were that it was somewhere between 2 and 4. It is now believed to be between 5 and 6.
That's very high. For comparison, seasonal flu is about 1.3, the H1N1 outbreak was about 1.5, and the 1918 pandemic was believed to be no higher than 2.8. Measles, on the other hand, can be as high as 15. Keep in mind that R0 values aren't purely intrinsic to the virus, they also depend on environmental and behavioral factors (so it can vary by locality).
https://www.harvardmagazine.com/2020/05/r-nought
See also
https://www.healthline.com/health/r-nought-reproduction-number#prevention