Back to the floor slab, thickness will depend on the reinforcing, concrete strength and proposed loads you want to place on it.
Currently building a warehouse, 180mm thick / 30MPa & SE92 mesh from memory. (Designed for 4t of racking + forklift loads)
Where any loads other than general racking are being applied, we've added 120mm of thickening 150mm wider than each item we're supporting.
May be overkill here, but personally I'd go for a 200mm thickening with cast in hold down bolts.
Way better than drilling and epoxying into after the slab pour.
Surely there's enough engineers on this forum to come up with a cost effective strong solution.