I suggest you look at some of the textbooks on mixed methods research, such as Creswell and Plano-Clark, or Fetters' The Mixed Methods Research Workbook. They cover this design in some detail.
I am in the field of didactics of English as a foreign language. The course I want to evaluate is the course of research methods that EFL students take at university.
The following articles could be good examples of using explanatory sequential mixed-methods design in EFL research. Here are the full citations.
Bakla, A. (2019). A mixed-methods study of tailor-made animated cartoons in teaching punctuation in EFL writing. ReCALL, 31(1), 75–91. https://doi.org/10.1017/S0958344018000046
Ebadi, S., & Rahimi, M. (2018). An exploration into the impact of WebQuest-based classroom on EFL learners’ critical thinking and academic writing skills: A mixed-methods study. Computer Assisted Language Learning, 31(5–6), 617–651. https://doi.org/10.1080/09588221.2018.1449757
Li, J., McLellan, R., & Forbes, K. (2021). Investigating EFL teachers’ gender-stereotypical beliefs about learners: A mixed-methods study. Cambridge Journal of Education, 51(1), 19–44. https://doi.org/10.1080/0305764X.2020.1772720
Zhang, L. J., & Cheng, X. (2021). Examining the effects of comprehensive written corrective feedback on L2 EAP students’ linguistic performance: A mixed-methods study. Journal of English for Academic Purposes, 54, 101043. https://doi.org/10.1016/j.jeap.2021.101043