Hi getting back into the game and was just wondering if kylo can use boost as a regular action and then use it again as a red action due to autothrusters? Thanks in advance

No.

Rules Reference page 3 under actions:

"• There is no maximum limit to the number of actions a ship can perform over the course of a round, but a ship cannot perform the same action more than once during a single round, or perform an action it has failed this round."

For further reference: https://images-cdn.fantasyflightgames.com/filer_public/93/da/93daf87a-d914-4306-aa28-e58ed14e60c6/b_swzrulesreference_v106_book-compressed.pdf

You're going to want to check the Rules section of the X-Wing Second Edition product page towards the end of next month too since there should be an update to the Rules Reference there (Wave 6 is adding another mechanic and there is probably going to be an update to the FAQ sections at a minimum). Welcome back.

37 minutes ago, Kapy said:

Hi getting back into the game and was just wondering if kylo can use boost as a regular action and then use it again as a red action due to autothrusters? Thanks in advance

Notice that Autoturster still uses the wording "Action". Since you've already performed a boost action, you cannot perform another boost action. It would need to specifically state that it is not a boost action to do what you are suggesting, such as with Anakin's Barrel Roll.