there are a few things you can do to increase your staying power.
The first starts with your health! I know yawn, but it is a MASSIVE part of sexual health if you want to avoid ED issues in the future. Weight is the first and then cardiovascular health is in there too.
I'm going to guess you want a faster solution that works for the now.
Double condoms can work if you have a fast trigger but a longer solution is work on your refractory period (short version how fast you can reload) and understand how your body works , tallguy suggested holding back that's called "the response cycle" and it works, when you know how it works and practice it ...ohhhh and working on those keagals. I know it seems like a lot of work but it well worth the efforts as you age the angle of the dangle will alter, working it now, will stop and limit that damage. Edging is easy to add into any sexual play. If you have a submissive ask them to lean the process too. She can then be used, to be your "fluffer" ..why use your own hands!

Most sub females like cock by mouth or hand..take advantage of that and make it fun to add in.
https://collarncuffs.com/resources/doku.php?id=multi-orgasmic
A cock ring will also help, excuse the Femdom site links but I'm to lasy to re type it all
https://collarncuffs.com/resources/doku.php?id=cock_rings
Best of luck.