Determine how many samples are needed to identify usability issues:
(Note! This study tests a relatively simple software interface and the tasks were quite direct. When the product is more complex, more testers are needed.)
Source: https://www.uxmatters.com/mt/archives/2016/01/how-to-determine-the-right-number-of-participants-for-usability-studies.php
Source: https://www.nngroup.com/articles/how-many-test-users/
If the study has a clear and specific target group, each type/group/segment needs at least 6 people.
For exploratory research, more samples are needed, and it is best to stop when no new information is entered. However, if you have to give a number, I think a group of 12 is safer. Add more if you expect more diversity in the participants.
Comparison of two groups: n = 120 with each group n = 60
Descriptive statistics in one market with reasonable accuracy: n = 150