Concurrent mixed methods research (CMMR) aims to cross-validate or corroborate the findings from two datasets (i.e., quantitative and qualitative data), while sequential mixed methods research (SMMR) intends to use the results of one dataset to underlie or explain the other’s—depending on the variant utilized. As David L Morgan has pointed out, choosing either CMMR or SMMR relies on the purpose of an investigation. You could go through Creswell’s (2022) concise introduction for instructive inputs. Here is the full citation.
Creswell, J. W. (2022). A concise introduction to mixed methods research—International student edition (2nd ed.). SAGE. https://uk.sagepub.com/en-gb/eur/a-concise-introduction-to-mixed-methods-research-international-student-edition/book276868
The decision to use the approraite mixed-methods research solely depends upon your research question/objective. It could have been better if you'd stated your RQ/RO here.
Other than Cresswell, I'd recommend you to read simple yet awesome research by Venkatesh:
https://www.jstor.org/stable/43825936
Article Guidelines for Conducting Mixed-methods Research: An Extensi...