Yes, mostly, and with fewer hoops than the Sussex-village setting might suggest. Newick has heritage constraints, but they sit in defined pockets rather than blanketing the whole village. Two conservation areas cover specific parts. Forty-two listed buildings are scattered across the wider area. Most homes here are outside both, and for those the standard permitted-development rules do most of the day-to-day work. The freedom to alter your house is average for a Sussex village, which is to say liveable rather than laminated in red tape.
On listed buildings, the numbers are what they are and they matter enormously if your house is one of them and not much if it isn't. Around forty-two listed buildings sit in the wider area. Three of them are Grade Two Star, which is the tier reserved for particularly important buildings of more than special interest, and the remaining thirty-nine are Grade Two, which is the standard grade for buildings of special interest. There are no Grade One listings in the mix. If your house is listed at any grade, listed building consent is required for any alteration that affects its character as a building of special architectural or historic interest, and that reads more broadly than most owners expect. It covers internal changes, chimney pieces, staircases, windows, doors, and often surfaces you did not think of as heritage. If your house is not listed, none of this applies to your walls and floors, and you are back on the standard planning-and-building-regulations track like anyone else.
On conservation areas, Newick has two. The Green in the middle of the village is one, and Church Road is the other. Both cover a specific and identifiable footprint rather than the whole parish, and the standard consequence of being inside one is that permitted development rights for certain external changes are curtailed. Painting a front door a colour you did not previously need to think about, replacing windows with a material the area's character discourages, taking out chimneys, adding solar panels visible from the street, felling or heavily pruning trees over a certain size, all these can require a consent inside a conservation area that they would not require outside one. If you are buying inside either of the two conservation areas, treat any planned exterior work as needing a conversation with the local planning authority before you commit money to it.
What all this means in practice for most Newick buyers is that permitted development still does most of the routine work. Single-storey rear extensions within the standard permitted-development thresholds, loft conversions with rear dormers where the size limits allow, garden buildings and outbuildings within their own limits, all of this remains available to any home outside the listed-building and conservation-area boxes, which is most of the homes in the village. Anything beyond permitted development, or any home inside either box, means a proper planning application and probably a chat with a local architect who knows how the Lewes District planners read the local pattern. There are no invented Article-4 directions or special orders to describe here beyond what the conservation-area status already implies, and it is worth checking the current position on any specific address before you assume.
The verdict on your freedom to extend is that Newick sits in the middle of the range for a Sussex village, which is the honest answer. The listed and conservation-area homes come with real friction. The rest come with the ordinary planning system and its ordinary constraints. Neither is a reason to buy or to walk away, but both are reasons to check the specific status of a specific address before you sign anything.