But from what you write you cannot manage budgets and deadlines.
Managing budget and deadlines is not about setting some "ideal world" and then whipping these lazy engineers to deliver exactly that.
Managing budget and deadlines is about - well we delivered X/Y at that date it already was $yyy in terms of money. If it went well maybe you can increase work load, maybe look at things again and stop gold-plating to move further. If it went wrong cut the scope - check what went wrong, lower the risk of not delivering by simplifying tasks. Check if maybe you miss some specialistic knowledge to hire someone to help and account that risk against budget or tell customer that you need something specific that they have to deliver.
I've seen more than once projects with ill-equipped team members. I've been one myself, too.
Even in established tech corporations, the process of team creation can be screwed up due to multiple reasons. I've seen DevOps engineers tasked with writing apps because PM did not checked what their role was. And that was a high-importance project in a huge, publicly traded, tech corporation.
Expecting engineers to estimate work they haven't done before ends up in guesstimation which is almost never correct.
PMs asking for estimations in pioneer projects create problems for themself, which they sometimes later blame on team members.
In practice, workdays are constantly interrupted by meetings. An 8 hr workday is effectively 2-4hrs product building. Than there are unforseen deployment problems, some requirements change, solve merge conflicts, perform code reviews, frameworks need vulnerability updates, etc.
An experienced PM knows this and should not use implementation time as project duration.
IDK, but this seems just psychopathic?
I think I missed the title, main topic or perhaps even what you were replying to when you wrote this. Maybe there is a context. In its absence, this reads like a HowTo for getting someone you already don't like, to quit.
Clear communication is a very important managerial skill, by the way.
Manipulative, psychopathic behavior, and you are a bad manager.
This is tinpot-tyrant stuff. I saw that in a movie: "no, the German people have failed _me_, they were weak, and deserve to suffer for it".