I am not sure of your question, so I will give two major possibilities. Everything depends on your aims

Can you randomize a larger sample to conduct qualitative research? Sure, if that suits your aims. You might also consider stratification, which could be done by many factors (e.g., demographics, a prior survey, etc.).

Can you conduct a qualitative study and then randomize for resampling for a second phase? Again, everything goes back to your aim, especially if you used the common approach of focus groups and then in-depth interviews. This approach is very common.

Notice, many qualitative studies have different sampling strategies, so I cannot say this enough: Your purpose dictates your sampling strategy. Also, bigger is not always better. Patton provides a great overview: https://legacy.oise.utoronto.ca/research/field-centres/ross/ctl1014/Patton1990.pdf

Read the following:

Gentles, S. J., Charles, C., Ploeg, J., & McKibbon, K. A. (2015). Sampling in qualitative research: Insights from an overview of the methods literature. The Qualitative Report, 20(11), 1772-1789.

Onwuegbuzie, A. J., & Leech, N. L. (2007). Sampling designs in qualitative research: Making the sampling process more public. Qualitative Report, 12(2), 238-254.

Thanks for enlightening on the matter, David Coker

Thanks a lot for the Answer Samuel Oluwaseun Adeyemo

If you use a small random sample, you need to understand that there will be not be any meaningful generalizability because your standard error will be be too large. Instead, I would recommend the typical qualitative approach of using a purposive sample that guarantees a meaningful set of participants.