You can make a condition of your offer to buy the lot that the seller, as the owner the  lot on which the house is built, grant you a view easement over that lot under which the seller would agree not to build any improvements or plant any vegetation which would obstruct your view. Generally that would be set forth in the deed to you and probably should have a plan attached which will show the location of the building on the other lot and that portion of the yard or other area on that lot over which your view is not to be blocked. There have been a couple of recent cases where the courts have determined that a view easement of that kind benefits the lot and it never terminates, as would a restriction after 30 years. Moreover the courts have also held that you as the owner of the lot with the benefit of the easement, would have the right to remove anything in the yard of the property next door which would obstruct your view for instance, a tree, high bushes or a fence. If the owner of that lot tried to build an addition on their home so that your view would be blocked, you could go into court and have the court order the owner to stop building the addition. In short,  you would have an enforceable property right in the property in front of you and you would be able to enforce those property rights yourself, if you can do so without a breach of the peace, or you can ask the court to order the owner to allow you to exercise your rights. Some care must be taken in drafting the language in your purchase and sale agreement and including it in the deed to you to assure that you will be protected after you buy the lot.