In order to secure transactions, some marketplaces want to offer escrow (money is hold for a certain time by a trusted third party) or deposit (seller take more than the price and give back the deposit at the end of the transaction).
With Stripe, holding funds (a bit different than escrow but close) is possible however deposit isn't.
Can you hold funds in your marketplace?
Yes, with Stripe. You can learn more in this article.
However PayPal doesn't offer this feature yet but they do offer pretty good protection for both buyers & sellers.
Can you allow deposit in your marketplace?
Right now this isn't possible. You could also advise your sellers to charge higher listing amount and ask them to refund them at the end of a transaction. However this relies totally on the honesty of each seller and PayPal fees would apply over the total amount and refund.