もしかしたら and its alternatives are usually treated as stand alone 副詞（ふくし） (adverbs) in Japanese that are used to present hypothetical situations, and what could happen within those situations. These expressions are a combination of the adverb 若（も）し, the 格助詞（かくじょし） (case marking particle) か, and one of several combinations of する
(したら, して, or すると). It is often translated as ‘perhaps’, ‘maybe’, or ‘possibly’.
As with many other Japanese adverbs, it will often appear at the beginning of sentences. Due to もしかしたら presenting hypothetical situations, かもしれない
will regularly appear in the same sentence (although it is not required).
Maybe, I will be able to go.
I may have to work, so I can't say anything for certain.
Maybe Ann-chan might come, but are you all okay with that?
As もしかしたら is a combination of もし
‘if’, か (presents a question), and したら ‘so happens that’, the literal translation is close to ‘does it so happen that’, or ‘should it so happen that’, with past or present tense being controlled more so by the following statement.
Perhaps I will take a day off tomorrow.
Perhaps it could have been yesterday.