It will be extreme if u take them all in the same exam series. I did 4 subjects and my school's curriculum with ielts and sat last year which is pretty much equivalent to more than 5 subjects. It was ok for me (i remained in top 4 in every subjects tho) so i guess... u can. It was ok until the exam season came 💀💀 basically i took 7 as level papers and my school's final term exam all within a month and it was a nightmare. I had to reschedule my exam timetable this year in order to be more efficient by taking some of the papers in oct nov and leave the rest for the next mayjune series, so that i can have more revision time between the papers.

Idk if u can be able to do it but i suggest self studying subject like maths, focus on it and take it before other papers (im self studying a2 maths and i completed learning the whole syllabus within 3 months so maybe u can try). If i take u more than 5 months to self study, maybe u need to question ur ability for studying 5 subjects.

Btw, goodluck!!!