I would like to ask what are the compatible car seats that can be used with the Joie Litetrax 4 DLX? Do I need adapter too?
Since Joie Litetrax 4 DLX is a no-adapter system, you can only snap a Joie car seat, in particular a Joie Dedicated car seat that is sold in a travel system with the pushchair. Not everywhere is this system sold. However, that dedicated Joie car seat snaps on the child's bumper bar, which is why only that car seat works - it has a wedge in the back that just fits on the bar. No other brands' car seats are officially compatible to be paired with this stroller.
However, if there is a Joie Litetrax 4 DLX carrycot compatibility available in your country, the carrycot adapters actually accept Joie, Cybex, Maxi-Cosi, Kiddy, Recaro, Nuna car seats.
Try googling 'Joie Litetrax DLX travel system' or write to Joie's customer service about availability.
And check also the Joie Litetrax 4 (without the DLX in name) that does have adpaters for Joie, Maxi-Cosi, Cybex and more car seats with the same attachment system available.