I bought a 256GB V60 Lexar brand memory and my osmo pocket did not accept it.

Read post #7 in this thread and see if the "SD Formatter" works to solve the problem.

SD Formatter

Hello and good day Josepilar94. Thank you for reaching out and for the inquiry. I would suggest using the supported SD card for the DJI Osmo Pocket for compatibility and reliability purposes. Actually, there is a possibility that the 256GB V60 Lexar SD card will be able work on the DJI Osmo Pocket. However, since it's not yet optimized and tested by DJI we cannot guaranteed  if it will work all the time with no issues while using it on the said device.  Just a friendly reminder that  it is recommended to use the supported SD card for the DJI Osmo Pocket for compatibility and reliability. In addition I will be posting the list of suggested SD Card for the said drone. Thank you for your understanding.

Interestingly the Lexar card that DJI have tested as working also has the A2 standard stamped on it similar to the SanDisk specified cards.
None of the other Lexar micro SD cards on the Lexar site have that designation including the one you bought.
The A2 designation is supposed to enable better communication with apps at the same time as recording video.
I have no idea if this has any effect on whether a card works or not as I only bought cards with the full card specification set out by DJI.
If your Osmo Pocket will not accept the card from the off there is little you can do about it as (from packaged) it should have been formatted correctly to use in the Osmo Pocket although the first job when inserted should then be formatting the card again using the Osmo Pocket.
If you have just got your Osmo Pocket then do read the setup instructions on the Mimo app on your phone before use.

To add to my last comment.
If you have just got your Osmo Pocket do not put the micro SD card in until you have registered your Osmo Pocket online with your phone using the DJI Mimo app.
Have a look at the setup video here.