Here are several luxury Sri Lanka resorts that explicitly advertise either guaranteed early‑check in / late‑check out in some offers, or flexible/subject‑to‑availability early/late check options — plus quick tips for getting the benefit.

Top picks (what they say about early check‑in / late check‑out)

• Anantara Peace Haven Tangalle (Tangalle) — some published packages (e.g., Pool Villa Exclusive / seasonal offers) guarantee early check‑in (from 10:00) and late check‑out (until 16:00) for qualifying bookings; other offers note early/late are available subject to availability. (anantara.com)

• Shangri‑La Hambantota (Ambalantota / Tangalle area) — Shangri‑La promotions and member offers include early check‑in and late check‑out (usually subject to availability), and members may get enhanced flexibility. (shangri-la.com)

• Cape Weligama (Weligama) — check‑in generally from 14:00 and check‑out around 11:00; early check‑in / late‑check out are offered but are normally subject to availability and may incur a fee. (expedia.ae)

• Amanwella (Tangalle) — standard check‑in/out times are ~14:00 / 12:00, but Aman properties commonly grant requests case‑by‑case (some sources report flexibility for late check‑out up to ~18:00 subject to availability). Contact Aman reservations directly for confirmation. (hrs.com)

• Taj Bentota Resort & Spa (Bentota) — Taj has offer packages and staycation promotions that explicitly include early check‑in and late check‑out; otherwise early/late are typically subject to availability or a fee. (tajhotels.com)

• The Fortress Resort & Spa (Koggala/Galle) — standard times 14:00 / 12:00; the resort says early check‑in and late check‑out can be pre‑booked via reservations (subject to availability). (fortressresortandspa.com)

How to secure early check‑in / late check‑out (practical checklist)

• Book a package that explicitly guarantees early/late check (some resorts publish these offers). (Example: Anantara pool‑villa packages.) (anantara.com)
• Join the brand loyalty program (Shangri‑La Circle, Taj/IHG/Taj membership, etc.) — members often receive priority for early/late privileges. (shangri-la.com)
• When you book, add your flight/arrival time and request early check‑in / late check‑out in writing; follow up 48–72 hours before arrival. (Most resorts list reservation/contact channels on their sites — contacting reservations directly is effective.) (aman.com)
• If the hotel can’t grant it for free, consider: paying for a guaranteed early‑check (day‑use rate) or booking the room for the preceding/ending night.
• On arrival day, be polite but firm at the front desk; if a room isn’t ready, request luggage storage, access to pool/club facilities, or a day‑use room until your room is ready.
• If you need a guaranteed specific time, book an offer that explicitly guarantees it — otherwise it’s almost always “subject to availability.”

Quick sample message to send to reservations (You can copy/paste and adapt) Hello — my name is [Your Name]. I have a reservation (confirmation #[number]) arriving [arrival date] on flight [flight number], ETA [time]. Could you please confirm if early check‑in at [requested time] and late check‑out at [requested time] are available for my booking? I’m happy to pay any applicable fee or upgrade if needed. Thank you — [Your name] / [phone number].

Final notes

• Policies and promotional offers change frequently (packages and guaranteed early/late check clauses are often seasonal). If you have specific travel dates, I can look up current offers and contact details and check which of these resorts have published guarantees for those exact dates.