السلام عليكم ورحمة الله وبركاته، If one doesn't know arabic, we know that we can make du'a in our own language in sujood. Does the same apply to the last tashahhud? Can we also make there du'a in our own language (after Tahiyat, Ibrahimiyya)? بارك الله فيكم وجزاكم الله خيرا

Yes, the same rule applies before the taslim as it does in the sujood. Whatever dua you are able to say in Arabic, say it in Arabic, and whatever you genuinely cannot express in Arabic, you may ask for in your own language. This is in the obligatory prayer and the voluntary alike, and do not fall into waswas about it.