Yes, but there’s a bit of nuance. Here’s my advice, for American English.
Leaving aside “today and.” and simply focusing on how you can describe planned or anticpated future actions, you can use the verbs be on, go on or start here, in either the future indicative, future progressive, present indicative, or present progressive. (With the exception that “*I am being on planned leave” is unidiomatic.) The present tense is less formal, and some teachers might consider it a grammatical error in formal writing.
Ways you could say this include, “I am going on planned leave tomorrow,” “I will start planned leave tomorrow,” “I am on planned leave tomorrow,” and “I will be going on planned leave tomorrow.”
You could also say, “I plan to go on leave tomorrow,” or several variations of it. This emphasizes the tentativeness: “I am going on leave tommorrow like I planned,” expresses certainty about what will happen. “I am planning to go on leave tomorrow,” means that is currently the plan, but it might change. “You are going on leave tomorrow,” is an order, direct enough to be rude. “You will be on leave tomorrow,” informs someone that they will be put on leave and do not have a choice in the matter. But it’s possible to soften this: “Right now, you are going on leave tomorrow,” sounds literally like the tenses make no sense. But, given the previous examples, we can figure it out. The plan right now, at the moment, is that you will go on leave tomorrow, but it is still provisional and you can get them to change it.
Thinking about it, I’m more likely to use the present indicative for planned events in the short term. I’d probably say, “I will retire at 67,” or “I am retiring at 67,” and probably would not say, “*I retire at 67.” On the other hand, “When I retire at 67,” sounds just fine to me.