First, the "senior" level is going to be different for each company. And, we also don't know your current skills. Are you a QA analyst (no automation skills)? Are you a QA Automation Engineer/SDET? Do you not distinguish between these and say that a QA Engineer or Quality Engineer can do both analysis and test automation? (The last one is how it should be to me).
In some companies, moving to a "Senior" role is just about years of experience. So, if you have 5+ years of experience, a lot of companies see this as Senior level. I think that's wrong since it usually doesn't care about skills or experiences, which are important. And it sounds like skills are important to you based on your question!
In other companies, moving to a "Senior" role is about influence and relationship building. In a lot of cases here, it's not about skills, but about solving your manager's problems, being their go-to person. It's about "who you know, not what you know." It's about being seen by leaders and showcasing/vocalizing/demoing your work as a problem solver or money maker!
My biggest recommendation is to look at job descriptions for "senior QA engineer."
- Do you understand everything listed in the job description?
- Have you performed the skills listed?
- Can you explain how you've utilized the tools or similar tools listed?
- Can you identify skill gaps from what you have and what is listed? If so, can you find a way to build those skills you lack in your current job/company?
If you can confidently explain each item, skill, tool, process, etc, listed in the job description, and the pros/cons of them, then you're on your way to this role and I'd encourage you to even apply to those jobs!
What's common is that the higher the role, the more important people skills become over technical skills. You'll have greater influence and responsibilities, so be sure to find projects to lead. What does this look like?
- Have you mentored, coached, or trained anyone in your job or in a skill you use? Since testing is rarely taught, have you or can you teach on QA skills, techniques, and fundamentals? I've run training sessions to teach developers on these!
- Have you built any test automation frameworks from scratch?
- Have you been responsible for tool selection? Being able to explain the pros/cons of your choice and why it's the correct tool for the job?
- Have you created any training documents?
- Have you improved the SDLC or process your team uses to gain efficiencies?
- Have you created and/or run a Community of Practice?
- Have you led any of the Agile/Scrum ceremonies like standups, retros, sprint planning, etc? If not, see if you can lead this as they are good ways to learn leadership and communication skills!
- Have you created or run a bug triage meeting?
- Have you created any new processes for your team? Why did you do this? What need did it fill or problem that it fixed?
- Do you wait to be told what to do? Or do you take initiative?
- How have you collaborated with people in other roles: dev, UX, DevOps, leadership, customer service? Can you explain how you've collaborated with these roles? The higher you go the more likely you'll need to collaborate with these other roles.
Ultimately, in my experience, Quality Engineering is about 3 things: people, process, and product, in that order! So the more experience you can gain in helping people, improving processes, and bettering products, the more equipped you'll be for Senior-level roles!
Also, I wrote an answer a while ago about skills between a QA automation engineer and a DevOps Engineer. A lot of what I wrote there can and does apply to a Senior QA Engineer, so I recommend reviewing it!