How to tell the boss to ask for a raise?

What's the reason for your salary increase? If you want more, the better, then I advise you not to mention it. Even if the boss gives it to you, you will get the short-term advantages and lose the long-term benefits.

If you do have a reason to raise your salary, such as: the workload is really heavy, the ability and salary don't match, the post salary is unreasonable, other companies hired you with high salary, and the salary can't meet the needs of life. Then tell the boss directly what the reason is!

Never think that a "talking" boss will raise his salary. It is a good thing to raise his salary! Not necessarily!

Don't treat the boss like a fool. The boss can start the company from scratch, from small to large. Generally speaking, the boss is "wise"!