is there any mentorship programme to learn code archetucture for senior developer position?

I am kind of a senior developer but I feel like I'm lacking skills, by observing and by gaining experience i feel like I'm lacking architecture skills to write a codebase which will support millions of user and for long term projects, although by continuous learning I'm improving but still I'm not satisfied with the progress rate.

I found a course which will I think help me grow was a developer on https://academy.essentialdeveloper.com/p/ios-lead-essentials-cohort-17-c0f4 but the prices is very high and can't afford it, can anyone suggest where I get some similar kind of mentorship with some reasonable price ?

***NOTE ***- I'm not sure if its right to post this kind of question here but I think developer can help another developer