It has long been known by everyone capable of reading biblical Hebrew that the Hebrew word "almah" can mean "virgin." Christophe Rico far exceeds this fact in his conclusions reached from his thorough semantic study.
Get Christophe Rico's book here: https://www.amazon.com/Mother-Infant-King-Isaiah-14/dp/1498230172/ref=sr_1_5?dchild=1&qid=1601352320&refinements=p_27%3AChristophe+Rico&s=books&sr=1-5
See Peter Gentry's helpful lecture here: https://youtu.be/ISzUGwIS0u4.