Then you need to remove a section of the pavers. Get handrail anchors, bond it to the deck bond wire or use non bonding handrail. Pour a concrete base to set anchors in. Re install pavers on top of concrete.

Edit. And hope there is no shallow plumbing where the handrail will go.

https://www.amazon.com/S-R-Smith-AS-100B-1-90-Inch-Diameter/dp/B002FL54DA/ref=asc_df_B002FL54DA/?tag=hyprod-20&linkCode=df0&hvadid=167163693584&hvpos=&hvnetw=g&hvrand=8872824609214341734&hvpone=&hvptwo=&hvqmt=&hvdev=m&hvdvcmdl=&hvlocint=&hvlocphy=9011035&hvtargid=pla-308525237890&psc=1