My understanding is that the sentence

I will have played tennis.

is future perfect.

But, what happens if I substitute the word "will" with a modal such as "could" or "ought to"? Does that change the tense? If so, what tense is it?

For example, what tense is the sentence

I could have played tennis.

Does a similar mechanism come into play for the sentence

I will have been playing tennis.

(future perfect continuous) vs.

I could have been playing tennis.