Career Progression on Resume - How much to embellish?

I'm an engineer with about 4.5 years of experience. I've had 2 jobs since graduating university. The first was a small startup (<10 people) where I did backend engineering and worked like a dog. The second (and current) is a large (~1500 people) company that's far more chill.

I've heard, read, and generally understand that recruiters (and probably hiring managers as well) like to see career progression when reviewing resumes. Makes sense.

My questions are:

1. rather than calling myself "Backend Engineer" for my first job on my resume, should I say I was a "Junior Backend Engineer"?

2. for my current job, rather than calling myself a "Data Engineer", can I call myself "Senior Data Engineer"? My company isn't technically advanced to the point where they formally use the title "Senior" engineer for anyone (although engineers definitely are paid differently based on tenure, impact, negotiation skills). Hence I feel like I have that lee-way. Heck, it might even be better to arbitrarily take the 3 year block at the company and pick a point around the 2-year mark where I say I became "Senior", so I can have Junior -> Intermediate -> Senior on my resume.

There's irony in down-leveling myself for my first job, although I really was junior and titles are fungible. As for up-levelling myself in my current role, isn't the point of a resume just to get an interview? And are people really going to check with my employer and say "aha, caught you! you said you were a Senior Engineer, but really you were an Engineer!" and even if people do, I would imagine it's a small number, that's offset by the upside of demonstrating that progression, even if it is a little messaged'

Finally, to address a question that will probably be asked, I definitely feel like I have learned a good deal since I started 4.5 years ago, technically, but more importantly knowing what to work on. Prioritization, time management, etc.

Thanks!