This is a multinational, multicenter, randomized, double-blind, placebo-controlled, parallel, Phase 3 study for treatment of participants aged 12 years and older diagnosed with moderate-to-severe atopic dermatitis (AD). The main objective of this study is to evaluate if those participants who received amlitelimab dose 1 in the parent studies (EFC17559 \[COAST-1\], EFC17560 \[COAST 2\], EFC17561 \[SHORE\]) and were responders can maintain their response either remaining at dose 1 or switching to dose 2 of amlitelimab compared to treatment withdrawal. Study details include: The study duration will be up to 68 weeks including a 52-week randomized double-blind period, and a 16-week safety follow-up for participants not entering the LTS17367 (RIVER-AD). The study duration will be up to 52 weeks for participants entering the LTS17367 \[RIVER-AD\] study at the Week 52 visit of EFC17600 (ESTUARY). The total treatment duration will be up to 52 weeks. The total number of visits will be up to 15 visits (or 14 visits for those entering LTS17367 \[RIVER-AD\] study).