No. Store credit generally has a specified place of use and may have expiry or other conditions. Check the refund destination and terms before assuming the money is freely available again.

Find the refund destination. Will the refund go to your payment method or back to the shop?

Shopify documents store credit as a merchant-managed balance and allows an expiry date when credit is issued. Check your seller’s policy to see whether your credit has an expiry date.

In an invented return, a $90 payment becomes $90 of shop credit. To use it on a $110 item, the person must pay another $20. The credit preserves some buying value while directing the next transaction back to that shop.

Where can you use the refund. The same refund amount can leave you with different places to spend it.
The same refund amount can leave you with different places to spend it. View larger.
Read the diagram
Where can you use the refund?
ItemQuestion or meaning
Bank accountMoney returns to the stated payment method.
Shop creditYou may have to spend it at that retailer.
ConditionsCheck expiry and which items it can buy.

Compare that with $90 returned to the original payment method. Bank-account money can be spent elsewhere. The shop credit may only work with that retailer.

Check expiry, exclusions, minimum spend, account requirements and whether shipping can be paid with the credit. A $90 balance restricted to selected products might leave part unusable for the task you actually have.

Keep the return confirmation and the stated refund method. If the method differs from what was agreed, ask the seller to explain or correct it. Your contract and local rules determine the refund you are owed.

Sources

Shopify: Store creditMerchant documentation of credit and expiry; actual merchant terms determine use.