i need to send pics via sms.

i have a galaxy S6 mini, old phone, doesn't have rcs on it!

Or just send an email

or just enable mms. then everyone on older phones can still send images via text.

Mms is enabled you just have to pay. No one offers free mms anymore.
Also if you are able to download Google messages it will enable rcs bypassing the native sms app.
Other than that your options are.
1 - email images
2 - WhatsApp images
3 - pay for messages
4 - install google messages if possible which allows rcs.
5 - upgrade phone 10 years old now
6 - share link to image on Google drive etc
7 - send over Facebook messenger

Tell them to enable RCS chats or iMessage.

my galaxy S6 mini doesn't have rcs on it.

Then as said upload image onto image sharing sites and send them link.

too fussy, sharing image via mms is way easier.
Superuser25

...if you are able to download Google messages it will enable rcs bypassing the native app

Superuser25 i don't use google wherever possible.

That's Strange running an android phone built on Google operating system

Other than that not much you can do.

They will never offer free mms sending as dead technology coming to end of life now RCS and WhatsApp exist along with signal / Facebook messenger and all that.

That's Strange running an android phone built on Google operating system

yeah tell me about it!
its a galaxy S6 mini, it's an old phone now. i also couldn't use it for my three wireless hub because it said it was too old.
these POS parasites who prevent back compatibility, i think it should be law.

It's all about security your device was supported for years its now over 10 years if you know how to add a 3rd party operating system can do that.
Though with limited ram and cpu speed I wouldn't expect it to be great performance.

Superuser25 can't stand lack of backwards compatibility. tech companies are pirates.

You had support for a long time your device is ancient you cant expect tech companies to support a device that is over 10 years old. It doesn't support modern wifi standards or newer encryption.
Thats like saying why can't modern games support my 10 year old computer. It doesn't have the hardware / software to do that.
If you dont want to change then just expect to not be able to use modern features.