After the year can u get the bonus sign up ?
Or it’s just the upgrade
The green comes with 30k how much is it in cash ?
If you upgrade to Gold, you will not receive the sign-up bonus. You will have to apply for the Gold directly.
It's a very bad idea to redeem MR points for cash (statement credits, really). The redemption value is so low, you'd be losing out massively. That being said, 30k MR points can be said to be worth $150 to $300 depending on what charges you redeem them for.
My friend just applied for the Amex green card with the annual fee $150 but she regrets not doing the gold
Can you change after the approval for the gold cars or you have to wait?
I'm not sure what there is to regret about getting the Green now. Dining earns 3 MR, nearly as much as the 4 MR on Gold. Travel points earnings are better on Green. The only area where Gold is better is groceries.
Many posted questions of this type come from those who jumped too fast to apply for a particular card. In those cases, it is better to just stop applying, get to know the card you just got, research the "new shiny" that you just saw, and in a few months maybe get the "new shiny" if it really makes sense.
The Green and the Gold are not mutually exclusive, one is allowed to have both, and it is possible to app the Gold in a month or two, if that makes sense. But think carefully before making the next app.
ETA: If this applicant only got the 30,000 MR SUB on Green, then that means the applicant is not seeking out the highest, once-per-lifetime AMEX bonus on each card. If going for the AMEX Gold, best to be patient and search for, wait for, the 50,000 MR offer to be available, and in the meantime, complete the Green SUB spend. More reason to slow down.
MR points are most valuable when transferred to airline partners for award travel. Other redemption options (gift cards, statement credit, etc.) are not very good at all.
You really should try to know not only what the rewards are worth, but what they are worth to YOU, before signing up for a card.
What do I get more using the flagship to travel or a Amex for travel ?
And to redeem it to travel purchases?
Your "friend" or you? Who has the Flagship? Your OP stated your friend just got the Green.