However, while it may strictly be engineering, and it's certainly good practice for a future engineering career; I think most engineers would still consider it a toy rather than a "serious" branch of engineering - so be very careful how you word things if you plan on including it as experience.
Certainly if you're building clever mechanical things with Technic and computer automation with MindStorms, that's good experience that might be worth mentioning, but if it's more about models with conventional System bricks, it's probably regarded more as a toy - although it's still good practice of engineering skills.
But the real engineering design starts within the highly skilled community you can see on bricks.com or brickset.com: talented creative people with real engineering. Models with 10k votes get productized by Lego as boxes (ISS, Staturn rocket). These are really great pieces of engineering in term piece placement and usage.
Bill of Material and instruction manual that you generate from there are powerful CAD tools similar to those used to design products. Fundamentals are there: views, coordinate referentials, interference...
Watch videos on "illegal technics" like https://www.youtube.com/watch?v=jWtZUzkvQ2E, it tells a lot on actual mechanical stress, aging, snapping...
I think yes, building lego counts as a type of engineering. I recommend being specific. Stress test and find the weak points.
It's easy to make things heavy and strong, try and make things light and strong.
1- Whats the minimum number of blocks you can use to create a bridge that is 20cm long and can hold 2kg?
2- Whats the minimum number of blocks you can use to create a bridge that is 20cm long and can hold 2kg, with a maximum block length of 5 per piece (meaning don't use any long lego blocks)
3- Do the same as number 1, but use a different bridge design.
4 - whats the minimum number of blocks you can use to create a bridge that is 10cm long and can hold 10kg.
5- you can also do the same, using glue and popsicle sticks.
Show us your work, write down what you discovered, keep a record of your work, journal it, share it.