Depends on what you mean by "can". You're certainly able to do so. But that's presumably not what you're asking here.
Can you do it without repercussions?
Define repercussions. If you mean getting fired or not, that very much depends on whether your job is defined by quota and if you are still achieving these quota.
But since you say there are no KPIs, then you've actually painted yourself in a corner. At face value, it's impossible for any outside arbiter to judge whether this is an employee who used to go above and beyond and no longer does so, or an employee who has stopped performing their duties.
Therefore, if you slack on your output, without any KPI to back you up that your output is still meeting the agreed workload, then the company is free to argue that you are no longer performing your duties.
Taking the example of at-will employment in the US, nothing (barring legally protected stauses like race, gender, ...) can guarantuee that you won't be fired.
Can you do it as a means of getting the raise you feel you deserve?
It's a dangerous game to play, one that I would not recommend. You've already found that the company is unwilling to pay you the salary you feel you deserve (whether you're being reasonable about the requested salary or not is actually irrelevant).
If you force their hand after they said no, even if you succeed, that's going to damage the relationship between you and your employer.
Personally, I would suggest simply looking for an employer who is willing to give you the salary you're looking for.
- If you can't find anyone willing to offer that salary, this may be an indication that your expectations may be unreasonable.
- If you can easily find someone willing to offer a salary you're happy with, that's a really good reason to jump ship and join that company.
In either case, you win. Either you reconsider your expectations without first offending your current employer, or you find what you're looking for without having damaged the relationship with the employer that you're going to keep working for.