I would look into Series I Bonds from the Treasury. In exchange for some limitations on buying ($10k/yr maximum) and cashing them out (not possible until 1 year minimum), they’ll handily beat the return of a HYSA and will inflation-protect your money to ensure you don’t lose any buying power over that timespan.

Investing in the market over just a span of 4-5 years is risky and you’d have to contend with the fact that not only could your lump sum have less buying power - it could potentially be wholly less than you started with, depending on how the market performs