Should be theoretically unlimited (This is in terms of bank transfers, and not debit card spending.).
Debit card spending has a hard cap, in addition to the top-up verification limit. This is imposed by Wirecard, Revolut’s debit card issuer. Details here: https://www.revolut.com/cardholder-terms).
Bank transfers (‘Payments’/‘transfer’ option in the app.) will be limited by your top-up verification limit. If you are planning on such a large purchase, you will have to undergo additional KYC/AML checks (e.g. Providing source of funds.).
Please see the attached post below. Click/tap the rightwards-facing triangle to expand content.
Best confirm with @anon33247966 for this, however.