"Isaiah Thomas is ready to fulfill a dream on the football field.
"The UC Davis football player, a senior defensive back who played a major role on this fall’s team, announced on social media Thursday that he has declared for the NFL Draft, which is scheduled for April 28 to 30...."
From the NFL.com site:
“Any college player who has completed four years of college eligibility, as distinguished from those who had a redshirt year, will be considered eligible for the 2022 draft unless a player submits a request to not be considered for the draft to the league by Feb. 4, 2022”.
Thomas doesn’t need to declare.
Thomas has been with the team for six seasons, redshirting his first year and hardly missing a game in the five seasons he played. Declaring is just a publicity stunt.