Working visa for language school?

I was reading this https://visa-station.jp/shurou/senmongakko-ryugaku-shurou-visa/
and it says 語学を活かした空港旅客業務 falls into 国際業務 category.

I'd like to know if it's possible to go to a 語学専門学校 and then work as a flight attendant in japan and apply for international services visa.

If not, what job can give me a visa after graduation? Thanks!

You will be eligible for a work visa if you complete a “senmon-gakko” with a certificate/diploma called “senmon-shi” (and of course find an employer). So for any course you might want to enroll in at “senmon-gakko,” you’d have to check if this “senmon-shi” diploma will be given. Your job will be limited only to those in that field.

By the way, exactly which 語学専門学校 are you referring to? Places like Kanda Institute of Foreign Languages? For example, they have courses for training students to become translators, interpreters, flight attendants, airline ground staff, international hotel staff, etc., in addition to English language teachers at kindergartens or elementary schools, as well as those who want to enroll later into an affiliated university. I guess those courses assume that the applicants already know the Japanese language (or that the applicants are Japanese).

If you mean Japanese language school (for non-native speakers of the Japanese language), no, because they are not “senmon-gakko” in the first place, and they provide courses mainly for people who want to first study the language then go to a college/university to study further.

If your aim is to find employment with an airline company, you might need to study the Japanese language first and then attend a “senmon-gakko” like the one I mentioned above that specializes in getting their students prepared to work as flight attendants, provided they give you “senmon-shi” status upon completion.
If you find a “senmon-gakko” that offer courses in the field you want to work in, you might want to contact that school to ask about the job prospects/visa situation (if they give “senmon-shi” diploma) for non-Japanese students graduating from that school.

But I might suggest attending a regular university – this will of course open up your career paths to other fields, as one of the requirements for other jobs (not specific like “flight attendant”) tends to be at minimum a bachelor’s degree (4-year university, in the case of Japan). For a work visa, you’d need to have an employment offer from a company in Japan, so exactly what job you might be able to find when you graduate depends on the situation/economy. Best wishes.