I have 2.5 year old and want to know if a pillow and duvet are safe for this age group and if you have any advice around type of pillow etc if so

Red Nose recommends to withhold the use of pillows until baby is in a bed & at least 2 years of age.
https://rednose.org.au/article/at-what-age-can-i-introduce-cot-bumpers-and-pillows
https://rednose.org.au/article/can-baby-use-a-pillow-to-prevent-flat-head

Red Nose has no recommendation in relation to the type of pillow or quilt/duvet.