Of course this is possible to jump up a few grades! In y10 I was a grade 4 in foundation maths and by y11 I was a grade 8/9 student in higher maths. I really did struggle at the beginning of the year so got out the textbook and did an half an hour a day of maths during autumn term of y11 I essentially tried and exhausted all the questions I could find (past papers, textbook, maths genie). For my mocks I achieved a grade 6, I then went to all lunchtime and break time maths support sessions and started using the youtuber The GCSE Maths Tutor, which really helped me target my weaknesses and go up another grade. I used his online platform for a while(needs a small payment but is on discount during exam season) and he offers free predicted papers which I mostly used just for some more practice.
In the exam season term I did targeted papers that I found on a website called My Maths Cloud, which offered Grade 7 and Grade 9 targeted papers as well as shadow papers (released by edexcel and other exam boards but not acesssible on their website) that contained a lot of problem solving questions the sort that you see at the back of the maths paper. I used the youtuber Mitchell Dye alongside these as he offered walkthroughs of these papers.