Download Oracle Instant Client libraries (URL may change, already happened few times). Be sure you download correct (x64 or x32) architecture. And correct version.
Last time I used Client 23.26.2.0.0 with Oracle 12c and PHP 8.5.
Before that Instant Client 23.8.0.0.0 with Oracle 12c and PHP 8.4.
Before that Instant Client 23.6.0.0.0 or 21.5.0.0.0 with Oracle 12c and PHP 8.1 and 8.3.
Before that Instant Client 21.3.0.0.0 with Oracle 12c and compiled with PHP 8.0, 7.4 and 7.3 fine.