Maging is not the same as "to be" in Spanish or English. Ser/Estar are conjugated as well as "to be" (is, am, will) in English. Maging is hardly conjugated the same way (naging - became, nagiging - becoming, magiging - will become). It is even conjugated differently from other verbs
Maging is more of "to BECOME" than ser/estar or to be.
Ser - soy(I am), eres(You are), es(he/she/it is), somos(we are), son(they are)
The Tagalog for these ones will be ako ay, ikaw ay, siya ay, kami/tayo ay, sila ay.
To say that the Spanish estar/ser and English to be has a Tagalog "equivalent" will further confuse learners.