The California purchase agreement already states that the property is being purchased "as is", meaning that the seller is under no obligation to improve anything about the condition of the property before you buy it. I remind buyers of this fact to manage expectations that a seller will repair or otherwise make any modifications for their benefit. Every buyer is buying every property As-Is, but when a buyer makes an offer to purchase a property, they typically request an investigation contingency as part of that offer, which allows them some specified period of time to have the property inspected by professionals, and gain a thorough understanding of any defects, their severity, and the urgency of any remedial actions. This contingency allows the buyer to cancel or negotiate credits for repairs in the event that any expensive items come up in the inspections. A $30,000 sewer line repair might really throw off the affordability calculation for many buyers.
In some very competitive markets, buyers have been encouraged to wave that contingency, thereby telling the seller that no matter what comes up in an inspection, they're still going to buy the place, reducing the risk to the seller of the buyer canceling after inspections. Even if you wave your investigation contingency, so that you're forfeiting your cancellation rights based on the condition of the property, you should still have home inspections done so you know what you're getting into. In California, sellers are required to make disclosures about the property they're selling, and all matters affecting the desirability of the property. These are typically delivered to the buyer once in escrow is opened, but sometimes they are given before making an offer. Even if the condition of the house seems very good, you might discover something in the disclosures that raises alarms, like learning of a violent event that took place there or the fact that it's under a flight path, or close to a known environmental hazard. If the buyer receives all the required disclosures upfront, before making the offer, it is less likely that such facts will surface later and derail the transaction.
In most cases, the home inspection is done after the offer is accepted, during the contingency period of the escrow. In very competitive listings or auctions, especially on properties requiring significant work, buyers will often bring their inspectors or contractors to evaluate the property before they make an offer. If seller disclosures are received, and inspections are performed before making an offer, it can sometimes make sense to put in your offer that you waive the right to cancel based on the condition of the property.
Buying a place As-Is does not mean you're buying a fixer-upper. It means that you won't you won't come to the seller with requests for repairs and credits, and you won't cancel the deal if you discover the place needs repairs.