The claimed benefits
Reduced muscle soreness, decreased inflammation, and various claimed effects on mood and metabolism have all been associated with cold exposure practices in various studies and popular wellness content.
Where the evidence is genuinely reasonably solid
Cold water immersion does show reasonably consistent evidence for reducing perceived muscle soreness after intense exercise, likely related to reduced inflammation and altered pain perception in the short term.
An important, less-discussed caveat
Some research suggests cold exposure immediately after strength training specifically may blunt some of the muscle-building adaptations from that session, potentially making it less ideal to use right after a hypertrophy-focused workout.
A reasonable, moderate approach
Cold exposure can be a genuinely useful recovery tool, particularly after intense endurance efforts or competitions, while being more cautious about using it immediately following a session specifically focused on building muscle.