For anyone interested in the 2024 rules changes, a pdf of the NCAA Soccer Rule Book can be downloaded from the NCAA website at https://www.ncaapublications.com/p-4692-2024-and-2025-soccer-rules.aspx Here's a few excerpts, but I suggest looking at the full document. As I read it for men's soccer, a player can play in each period (1st half, 2nd half, 1st OT, 2nd OT), but if subbed out cannot re-enter until the next period.
The following rules changes apply to Division I men's competition only.
Substitutions (Rule 3.4.3). Allows teams six moments to make substitutions
in a game.
Substitutions (Rule 3.4.3). Allows substitutions to occur during any stoppage
of play.
Substitutions (Rule 3.5.1 Exception). Eliminates reentry in the second half
for field players and makes all periods the same (no reentry).
3.4.3 For Division I men only, each team is permitted six substitution moments
during a game. A moment may be used during any stoppage of play, and up
to 11 players per team may be substituted for in each moment per Rule 3.3.
If a team is only substituting players under the exceptions of Rule 3.7, that
shall not count as a moment. If a normal substitution is made at the same
time as one under the exceptions of Rule 3.7, that shall count as a moment.
For postseason overtime games, each team shall retain any unused moments
from regulation play and receive one additional moment. Substitutions
during intervals between periods do not count as a moment.
3.5.1 Field Players. Field players are not permitted to reenter the game in the same
period after being substituted for in the first half, the first overtime period
and the second overtime period. Field players are permitted one reentry into
the game after being substituted for in the second half. Each overtime period
is considered a separate half, so a field player who is substituted for in the first
overtime period may participate in the second overtime period.
First half: no reentry.
Second half: one reentry.
First overtime period: no reentry.
Second overtime period: no reentry.
Exception: For Division I men only, a player who has been substituted for may
not reenter the game in the same period unless it is for one of the exceptions listed in
Rules 3.5.2 or 3.7. This includes overtime, where each 10-minute period is counted
as a separate period with no reentry