In some cases, yes, but it depends on the airline. Most airlines require GCSEs in English and Maths, usually at grade 4/C or above, due to the communication and numeracy skills needed for the role.
Some airlines may accept alternative qualifications, such as Functional Skills Level 2 in English and Maths, but this is not guaranteed and varies between employers. If you do not currently have the required GCSEs, gaining them can improve your chances of meeting airline entry requirements.
Because criteria differ between airlines, it is important to check the specific requirements of each airline before applying.