Yeah, you modify files in SteamLibrary\SteamApps\common\Cold Waters\ColdWaters_Data\StreamingAssets\default\cam paign\campaign001\missions folder.
Creating override folder, copying whole campaign folder into it and working there is preferable though. Otherwise any update will delete your changes.
campaign001 - 1984
campaign002 - 1968
Anyway in missions folder there are txt files describing various missions, you want to find that part:
Code:
NumberOfEnemyUnits=3-4,1-2,2-3,1-2
CombatBehaviour=DEFENSIVE,OFFENSIVE,OFFENSIVE,OFFENSIVE
EnemyUnitMissionCritical=TRUE,FALSE,FALSE,FALSE
EnemyShipClasses=wp_bdk_alligator|wp_bdk_ropucha,wp_bpk_kresta2|wp_bpk_kara,wp_bpk_kanin|wp_bpk_kashin|wp_skr_krivak1|wp_mpk_grisha3,wp_ssn_victor1|wp_ssn_victor2|wp_ssn_alfa
Ofc you change NumberOfEnemyUnits. 3-4 is a range, so game will spawn 3 or 4 landing ships.